Happy Father's Day... from your 22 kids (and counting)! 'Livid' wife of New York math professor finds out he's impregnated 18 women by 'donating his sperm' for free 

Professor Ari Nagel, 40, is the proud father of 22 children. All but one came from sperm he donated for free to single women and lesbian couples

A New York math professor who has fathered 22 children, many of whom were conceived in public restrooms, is in the dog house this Father's Day after his wife recently learned of his activities.

Ari Nagel has been donating his sperm to women for nearly a decade, and now he's got nearly enough children to fill a baseball team, 18 baby mamas to call his own and baby number 23 on the way after recently impregnating another single mother.

But after revelations about the prolific sperm donor came to light last week, Nagel's wife of 10 years and the mother of his three children, Roxanne, is 'livid,' according to the New York Post.

'She's been yelling at me a lot,' the Kingsborough Community College professor told the paper.

Nagel, who says their relationship has not been romantic in years, claimed his wife was aware he was procreating in his free time, but he said she did not support it.

'She always wanted me to be a regular, traditional spouse,' he told the paper.

He also noted she became bothered when he started donating to all the other women.

Nagel told the Post: 'When she saw me donating to all these women, she asked, "Why are they worthy and I'm not?"'

'She was never happy about all these other kids, but she tolerated it,' he added.

The 40-year-old said he and his wife were in a committed relationship when their son was born back in 2004, and about a year later they became husband and wife. 

But at some point, he said their marriage became one of convenience, noting the pair sleep in separate bedrooms, according to the Post.

Together, they have a 12-year-old son and two daughters, who are ages two and five.

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Nagel has been donating his sperm to women for nearly a decade. He's now got nearly enough children to fill a baseball team, and 18 baby mamas to call his own

Speaking to the Post outside the family's apartment, Mrs Nagel said she had nothing to say regarding the matter, adding 'what's done is done.'

She probably is not too pleased to know that following last week's news, her husband has since been inundated with messages from women 'all over the world' who want his sperm. 

'Almost all of them want to have a baby, but some want to hook up,' Nagel told the Post.       

His first donation happened eight years ago at a fertility clinic, with a single friend in her late 30s who wanted to become a mother.

Women have since found Nagel via Craigslist, word of mouth or Known Donor Registry, a free website connecting couples to donors who do not want to remain anonymous. 

It's an option that runs much cheaper for hopeful mothers than a sperm bank, where costs can range anywhere from $300 to $4,000, according to the American Pregnancy Association. 

Nagel offers his sperm up for free. Sometimes he and the mother-to-be will conceive the old-fashioned way, with lesbian couples sometimes holding their partner's hand in bed for moral support.

But more often Nagel's sperm is produced thanks to a couple of minutes of alone time with his cell phone, and delivered into a menstrual cup an ovulating woman can then insert in her cervix for up to 12 hours. 

And the women don't just flock to Nagel because of his free services or high sperm count. 

'He's a lot of fun to be around,' Tiffany Harrison, 41, told the New York Post. 'He loves people, he's outgoing, and he's gorgeous.' 

Harrison and her wife Yvonne have a toddler daughter with Nagel, one of his many children the father regularly sees for babysitting, birthdays and graduations. 

Nagel said he loves that his side hobby allows him to have a huge family without all the responsibility. Some children he'll see every week, but there are others he's never even met. 

Nagel often produces his sperm in a bathroom at Target or Starbucks before handing it off in a menstrual cup to a hopeful mother, who can then insert it into her cervix for up to 12 hours 

'I feel like I'm getting all the joy, but also getting a good night's rest,' he told the Post. 

But some mothers haven't been happy with Nagel's hands-off approach, and have taken him to court. 

The first five women that Nagel provided his services to successfully sued him for child support, although he claims they promised in advance they would never sue. 

'I don't know what's more surprising: that five sued or 17 didn't,' Nagel said. 'They were all well aware there was no financial obligation on my part.' 

Crystal, who has two sons with Nagel, said she had been under the expectation that they would co-parent together and feels her kids got 'left in the dust'.  

Despite losing half of his paycheck to his growing brood, Nagel is still talking to more women looking to have children. 

'This isn't time-consuming, and I'm doing it anyway,' he said. 'It's very easy for me to do.' 

And Nagel said he has no regrets when it comes to the family now spread across the world. 

'I just love seeing how happy the moms and kids are. That's why I do this,' he said. 

'It's the gift that keeps on giving.'