Not sure if it is worth him saying something to BM. She is going to do what she wants and she will just think that you made him say something and probably tell the kids. You can tell him you were hurt he didn’t defend you. He could have a conversation with his kids about what happened and explain that married couples are a team and make decisions together which is why you are involved in all decisions.
There is no point in talking to her when she is in that head space. Time will heal, lead by example and never lose connection with the kids. The truth will always prevail. My husband put a disparaging clause into his divorce agreement, perhaps something to consider? I’ve gone through it all, called all the names, it’s been nearly 7 years. Sometimes we want our man to speak up but it’s traumatizing for them too. You got this mama!
If it’s affecting your and the kids relationship I would have a conversation with her if he is not willing to address it