For me and my xabf, it took not responding to her phone calls directly and just responding back through emails. I have also made it clear that I do not want to talk about him though she does try. I just give one answer comments and/or reinforce the fact that I do not want to talk about him. He doesn't want to talk to her himself because he knows full well that it is a trigger for him and that no contact with her himself is the best for him to get on track because she will just throw money at him. But again, that isn't my problem and I think you have to just try to and enforce your boundaries because as my mother said about my xabf's mother "she wants you in the picture and with him and she will most likely use any tactic to see that happen whether it is guilt, manipulation, etc so don't let her get that far to make you feel bad for the decisions you have made and the boundaries that you are putting up for your own well-being". I know it is hard to have contact with your x's family but hopefully if you are firm and try your best to not let the communication escalate to any talk about him (I usually ignore any comments about him in emails, etc) then you can hopefully start having a relationship that is based solely on your kids. I know it is hard and I hope you find a way to get through this kind of headache.