I NEED ADVICE!!

So my best friend and her boyfriend broke up after 2 and a half years because he "didn't have time for her" and "wanted to experience high school" (he wanted to have sex with a bunch of different girls). At this point they have been broken up for more than a month and they are still having sex. She always complain about him but I am really tired of hearing it because I feel like she is bringing a lot of the stuff upon her self but I don't want to be rude about it wen I tell her not to talk to me about him unless they are done having sex. And I wrong for that? How do I tell her?