Nick Young's pregnant mistress is speaking out!

Keonna Green, who is pregnant with Young's second child, is opening up to Us Weekly, confirming that the b-ball star is the father of her unborn child and revealing that the affair happened during his engagement to Iggy Azalea.

Green, who shares a four-year-old son with Young and who was also high school sweethearts with the sports star, says the two got close again last September -- and that before long things got sexual.

Green explained, "We would take our son to Magic Mountain together. But sometimes Nick would say, 'Oh, there’s too much traffic,' and he’d just play with Nicholas in his room. We got caught up in the moment and it just happened."

Umm wow -- Magic Mountain? Yeah, that sounds super romantic ...

Green says she told Young to tell Azalea what was going on, "I would be like, 'Nick, you cannot be sloppy. You need to be honest [with Azalea],' He would say, 'I don’t want to hear it.'"

What a great dude!

Green also said she was up front about what was going on, saying, "I don’t know what was going on in his household, but me and Nick have lots of history. It wasn’t a secret on my end."

Despite all that has happened -- the not-remorseful Green says she has no regrets, and she doesn't think she was the only one that Young cheated on Azalea with. WELL OBVIOUSLY!

"I didn’t feel guilty because I was in love with a man, and I’m pretty sure I’m not the only woman," she told the mag.

Green also revealed that she found out she was expecting early on in the pregnancy after experiencing back pain, and is positive that Young is the father.

"It was 200 percent Nick’s child," said Green. (We wonder if she knows there's no such thing as 200% positive?)

Green also says despite the unplanned pregnancy, Young was there for her. "He’s always supportive, but he was in shock. With him being in a public relationship, he didn’t know how to handle it. We didn’t get into [how he would tell Azalea]. I felt it was his decision how to handle it."

Well it sounds like he waited a good long time to handle it -- Azalea and Young only split last month!

Green also says that she's attempted to make contact with the "Fancy" rapper. "I tried to reach out to her; I never got a response," she told Us. Green said that if she could speak to the rapper she would wish her "a lifetime of success."

Aww -- how sweet?! She slept with her fiance but wishes her success -- now isn't that thoughtful!

Amazingly enough, the pregnant lady said, "I’m definitely not going to apologize for being in love with a man who I have a lot of history with."

Green added, "I do wish her that kind of success and hope that she can get through this difficult time and she and Nick can move forward from this."

Sounds like with their morals Young and Green deserve each other!