My boyfriend's ex girlfriend keeps trying to talk to me

I've been with my boyfriend for 7 months and he's an amazing guy. Funny. Ambitious. Has a huge heart. He's a paraprofessional and loves working with special ed kids and is hoping to become a special ed teachers one of these days. When it comes to his ex's he doesn't have really anything bad to say about most of them except one. He had an ex named Sarah and he said he had never dealt with a more crazy, abusive woman in his life. He said she was the definition of crazy. He claimed she was a huge scammer. Faked being pregnant. Faked cancer. Lied about her children. Apparently she said she has 3 kids that her ex tricked her into signing away her rights but there dad was actually dead and she lost custody of them to her mom. That she was just an overall pathological liar and psycho. I had gotten curious and searched her one day because he claimed she had a criminal record which she did. She had one charge for fraud and another that I can't remember the name of the exact charge because it had a different name than what I'm used to seeing with crimes like that but the charge meant she as an adult had sexual relations with someone under the age of 17. Which when I did the math it means she was 24 and had sex with someone under 17. Idk if that meant 16 or 11. The charge just means under 17. It wasn't my boyfriend. He claims he wasn't that person and they met as adults. So she has been sending me message requests and friend requests lately. I looked at the message requests and it was her saying over and over again that my boyfriend is never gonna love me. My boyfriend told me to just block her and he's not dealing with her. Part of me just wants to see what she's wanting to say to me. But I also know it's stupid to entertain her

Edit: I wanted to add some clarifications since people are arguing in the comments. I use charge and convicted interchangably. She did 11 years for the sex with a minor stuff. 5 for the fraud