The news was buried deep inside the Roman news section of La Repubblica. None of the other papers even bothered with it: Cicciolina to go to jail. In the postage-stamp-sized photo, the tiny, peroxide-blonde, diva whose career has traced the history of Italy in the past 30 years clutched a Victorian doll, smiling the same too-broad, too-bright smile she has flashed at a thousand film cameras, the hard flat charcoal eyebrows crammed down over her cerulean eyes.

Far bigger was the photo of "Jeff Lynn Koons" as the paper styled him, Cicciolina's ex-husband, the father of her only child, Ludwig, and the reason she may, if this week's sentence is upheld on appeal, go to jail for failing to honour their custody agreement and preventing Koons from seeing their son. In the photo, Koons grins, wearing a pinstriped suit before the giant steel balloon-dog sculpture that stood for months last year outside Palazzo Grassi on Venice's Grand Canal.

It's a strange parable of the age, this long fight and its bitter conclusion: two grotesques of the age, she with her absurd political career just behind her, he with his look of a travelling brush salesman, manufacturing huge, knowing pieces of kitsch and persuading the art world to pay ever-more-swollen sums for them.

They met in 1987, and getting together seemed a brilliant career-move for both of them: she was 35, ready to crown her career as Italy's most celebrated porn star with a magnificently improbable liaison; while he, connoisseur of post-modern artworks of jaw-dropping vulgarity, who always teased, like Warhol and Gilbert and George, with the idea of knitting life and art in a seamless robe, now had a partner whose life, like his own work, was all on the outside.

The couple married in 1990, separated in 1992 and divorced six years later. She mournfully describes him watching videos all day while she was reduced to conversing with the dog. A son resulted however, young Ludwig. When they split, both claimed custody. A bitter and very expensive legal battle ensued, lasting 14 years and finishing yesterday, with a jail sentence for the woman who, as an Italian MP, once advocated sex for prisoners. No one doubts that there will be an appeal.

La Cicciolina, which means approximately "cuddles", was born Ilona Staller in November 1952, "after a long stormy night" as she records on her website, in the poor section of Budapest where, exactly 50 years later, she would stand unsuccessfully for election as a Hungarian MP.

Her destiny, she told Italy's L'Espresso magazine last year, "was written in the stars. I have had a very unusual relationship with sex since I was a child. I was curious about it, I enjoyed it, it made me feel powerful."

Coming of age in the late Sixties, when unbridled sex and female emancipation were considered synonymous, Staller was born at the right time – though not the right place, amid the repression and puritanism of the Warsaw Pact. But communism, too, had its lighter side.

"As a girl I worked as a waitress in a hotel in Budapest," she recalled, "and the secret service approached me and asked me to seduce foreign guests. I had to go in their rooms, make them talk, then photograph the papers I found in their bags.

"At the age of 18 I was agent Katicabogar [the Hungarian for ladybird], spy and comfort girl to Arab businessmen and American politicians."

It's not surprising she was picked for the work: photographs of her as a teenager show a striking beauty with a long straight nose and severe blue eyes, blonde hair swept back behind her ears. The avaricious, lustful grin that became her trademark was still a few years in the future.

In the course of her work she met an Italian travel agent, married him, and vaulted gracefully over the Iron Curtain, moving to Rome. The marriage, which may only have been for immigration purposes, quickly fell apart, but with her exotic looks, Staller soon found work as an advertising model for leading Italian brands. Then, in 1973, the sexually precocious Hungarian ladybird stumbled on the man who was to change everything.

Riccardo Schicchi, who had been kicked out of high school for spying on the girls' toilets, was a photographer looking for a lucky break, and in an Italy still beset by clericalism and in the clammy grip of Christian Democracy, the two of them set about causing trouble.

"He was a kid without a lira to his name, with a broken down old Peugeot which sometimes I had to push to get it going," she recalls. Together they launched a midnight programme on a station called Radio Luna with the unblushing title Voulez-vous coucher avec moi? It was a sex-chat show, a revolutionary idea at the time, featuring live contributions from listeners, and it took off. Staller came up with the term "cicciolina", an affectionate diminutive of the word for "fatty", thus "cuddleable" or "pinchable", as a nickname for her genitals. When it caught on, she took to applying it promiscuously to all the dirty-minded men who called in. Finally the name stuck to her, "La Cicciolina", she of the pinchable pudenda, and a brand was born.

The pair of them began systematically dismantling Italy's taboos, publishing photographs of the model in sexy poses, staging the first appearance of a totally nude woman in an Italian public place (La Cicciolina, naturally, in a discotheque), the first naked breast to make it on to national television, then, in 1979, Italy's first soft-core porno film. Within five years, soft had turned hard, but the star remained the same.

Today, La Cicciolina describes it as a natural and also enjoyable progression. "From when I was an adolescent I realised I was so sexy that every man wanted only and immediately to possess me: without sentiment, just out of libido. I don't regret any of it.

"You see, the character of Cicciolina, both naive and malicious, was not an act. It was really me. I was a spontaneous girl who liked to have sex, to show off eroticism, to shock the prudish... I liked to put on shows, to excite people, to make them smile. Making porno films was good work, and I'm not afraid to say that many times, on the set, I enjoyed myself."

She regretted none of it – but, at other times, she seems to regret the whole thing. "I repeat, I regret nothing – but I believe that I was never loved," she says.

No white knight ever showed up. Instead, in 1987, as she reached the far boundaries of what Italy would accept, a political grouping known as the Radical Party stepped in to make an honest woman of her.

The Radical Party was as much a child of the Sixties as La Cicciolina herself, exasperated with the vice-like grip in which the Catholic Church continued to hold the country, but equally contemptuous of the grey, Stalinistic verities of the other great alternative, the Communist Party. The Radicals, led by fat and flamboyant Marco Pannella, famous for being repeatedly arrested for smoking joints in public places, was for all those modern Scandinavian sort of things that the Church wouldn't countenance – abortion, contraception, dope, divorce and (why the hell not?) pornography, too.

In the most brilliant publicity coup of its short history, the party adopted Ilona Staller, and, although she was placed way down the list of candidates, she received enough personal preferences – 20,000, second only to the party leader Pannella – to sweep into parliament, and history.

Staller is proud of what she achieved as an MP. "I was an MP in the Italian parliament from 1987 to 1992," she says, "and I fought the fight for sexual freedom, the fight against every form of censorship, for sex inside prison and sexual information in schools, for education about Aids...." In other words she began to take herself seriously. She had lived a life which, in any other age, would have led to ignominy and disgrace. She had committed every sort of gross act – even today, "Cicciolina with a horse" pops up readily if you put her name into Google – for paying audiences, and every man she had ever met had screwed her rotten, one way or another. But now, thanks to the Radical Party, it all made perfect sense: she was a missionary for the new society.

Perhaps Staller didn't realise that this was just another form of exploitation, this time in suits and in parliament; more exploitation, for different and more abstract ends, but barely less cynical than that of the porno barons who had been making money out of her for the previous 15 years. For the Radical Party, she was a living, grinning stunt who put the party on the map. But five years was quite enough. In 1992 she tried to make it on her own, forming the "Party of Love" with her old photographer/manager Schicchi and Moana Pozzi, Italy's other legendary porn star.

But in truth, Staller was no politician, and the Party of Love was no party. It failed to pick up more than a handful of votes, and died.

That didn't matter, though, because respectability in another guise had come hammering at her door: holy matrimony. True, Jeff Koons may have seemed scarcely more plausible as a husband than, say, Michael Jackson, but he was famous, artistic, and in his oddball way, he seemed to idolise her.

The way Koons tells it, he had decided to turn himself into a porn star so he could have his image plastered across billboards, as part of a project sponsored by the Whitney Museum on the power of the media. It sounds wacky but, hey, this was 1989. He had been immersing himself in men's magazines as preparation for a previous project, and had seen and liked a photo of Staller in Stern magazine, adopting a mesh dress. Then, one day at an autostrada service station in Italy, he saw her image again, this time in a pornographic magazine. The picture had an Eastern European setting. "I'd never seen erotic images based in Eastern European culture," he said. "They tend to have strange, surrealistic fantasy backgrounds. So I was very attracted to the sets, but I was also very attracted to Ilona."

He arranged to do some photo sessions with her, based on The Expulsion from the Garden of Eden by Masaccio, which would be posed as imaginary advertisements for a non-existent porno film. "When we started doing these sessions," he said, "she started flirting with me, and before I knew it we had developed a relationship."

The art that sprouted from their marriage, "Made in Heaven", was like nothing he has done before or since, a collection of paintings, photographs and glass sculptures showing the two of them having sex, Staller wearing only white stockings, the pair of them romantically embowered in flowers. But once the pictures were out there for everyone to stare at, that was it.

This latest and most exalted form of exploitation over and done with, there was nothing left but to examine the bank accounts and plot the next move. There was nothing left to share. Koons stared at his videos, Staller chatted to the dog – then in 1992 out popped Ludwig. They were living in the US, but when Ludwig was 13 months, Staller upped and carried him back home to Italy. And so began the custody battle that has gone back and forth for the past 14 years.

After the couple divorced, the court awarded custody to Koons, judging Ilona "too permissive, incapable of giving an example", while Koons had shown himself "an affectionate and responsible father". On appeal, the verdict was reversed, custody awarded to La Cicciolina, but with visiting rights for Koons – rights that Ilona Staller, according to Koons's lawyer, has never respected. "Ludwig doesn't want to see you," she would say. Or: "Leave Ludwig and me in peace, we have rebuilt our lives together."

In March, Staller sued Koons in New York State Court, claiming that he owed her $2.3m (£1.16m) in child support. When an Italian court awarded her custody of Ludwig, it ordered Koons to pay $2,330 (£1,160) per month, but she said he had failed to do so.

This week, Jeff Koons's Roman lawyer insisted that there was no glee in his client's camp at the latest judgment. "This certainly does not make my client happy," said Stefano d'Ercole. "The only thing he wants is to see the son he adores, as he adores the other four children from his second marriage."

Of course, at this point, there is not much of Ludwig's childhood left to protect: aged 16, he speaks (his mum says) in typical Roman dialect and is a fan of the local football team Lazio. At school he has a bias towards sciences.

Motherhood and the presence of an adolescent son seems to have cured Staller of her libertarian fads. "I don't have anything to do with the world of porno any more," she has said. "My child is an adolescent, and I have had to block his access to porno internet sites because I don't want to risk him seeing videos of his mother." But, to date, Ludwig has exhibited no morbid interest in his mother's past, she says. "I've told him that in my life I've done lots of things, from singer to MP, and also porno actress. He didn't ask me any more about it. Once a friend of his suggested that they watch one of my videos, but he refused...."

So many brave libertarian ideas down in flames. If the last Italian election spelled doom for the Communists, none of whom made it into parliament, the Radicals didn't fare any better. And Riccardo Schicchi, the photographer who got Staller's show on the road all those years ago, was, earlier this year, sentenced to a lengthy spell in jail for offences related to prostitution. Only one man has sailed clear of the whole morass: Silvio Berlusconi, who in 1974, Staller claims, took her "in his private plane for a beautiful holiday on one of the most beautiful Greek islands".

Today, La Cicciolina watches Italian television, with its unending parade of well-tanned, half-naked nubile flesh and would like, if we don't mind, to receive some of the credit. "When I see all these half-naked showgirls at eight in the evening, I think, this would never have happened if we hadn't made a scandal and been denounced by everybody 30 years ago." In Italy's parliament, too, she could see herself as a pioneer: where she once stood, preposterously alone amid those velvet-covered benches, now there is a whole bevy of Berlusconi babes. Some of them are even ministers.

La Cicciolina, however, craves a more modest destiny. "I would like to be a wife who had been married to the same man for 30 years," she says wistfully, "with lots of children and grandchildren around. Instead, I am a woman alone... I did what I did, and I'm happy about it. But all the men around me exploited my sexy nature to take me to bed or to make money. As if sexual libertinism inevitably implied the absence of love and of sensitivity. I am a very romantic person, but nobody ever realised it...."

Life after porn

Matt Sanchez

Matt Sanchez, a marine reservist who has travelled to Afghanistan and Iraq as an embedded journalist, is an unabashed conservative, and made his name as a political activist while at Columbia University. Harangued by on-campus socialists for his support of the US military, he subsequently wrote an op-ed article for the New York Post in December 2006, complaining that the university had ignored his complaints and were prejudiced against the military. For this he was honoured at the Conservative Political Action Conference. It then emerged that Sanchez had appeared in gay porn movies under the stage names Pierre LaBranche and Rod Majors.

Traci Lords

Traci Lords supposedly named herself after Katharine Hepburn's character Tracy Lord from the classic rom-com The Philadelphia Story, but her own film debut was rather less auspicious. She became famous (make that infamous) for appearing in porn films and Penthouse magazine when aged just 16. Her first film, made in 1984, was called What Gets Me Hot! After her arrest for making adult fare while under age, Lords moved into the mainstream, appearing in films such as Blade, and television series such as MacGyver, Will & Grace and Melrose Place. She even sang for the Manic Street Preachers on their 1992 single "Little Baby Nothing".

Sharon Mitchell

Sharon Mitchell, formerly a famed lesbian porn performer, is now the director of the Adult Industry Medical Health Care Foundation, which she established in 1998. She appeared in more than 2,000 movies in the 1970s and 1980s, but her career took a dark turn when she became addicted to heroin, a habit she shook off in the 1990s. In 1996, she was brutally raped by a "fan" and left the porn industry. She founded her health organisation for adult film performers after acquiring a PhD in human sexuality from the Institute for Advanced Study of Human Sexuality in swinging San Francisco.

Linda Lovelace

Linda Lovelace (real name Susan Boreman) ended her life as an anti-porn campaigner. She starred in Deep Throat, the 1972 film which involved her engaging in sexual practices she later claimed were performed under duress. Indeed, she said her husband (and pimp), Chuck Traynor, regularly threatened her with a gun. After publishing her autobiography, Ordeal, in 1980, Boreman joined the feminist anti-pornography movement. She died following a car accident in 2002.

TIM WALKER

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