I’m not questioning your moral. Maybe you understood that way bc I told you that that rage you are feeling now, need to be slow down someway, in order to give you a colder mind and look for a more convenient solution for everyone.
I can figure out there are guys like that you describe but I want you to think about the best intervention possible.
So, I don’t think you are lying. But, I know how emotions can lead us to see the picture as fatal and lead us to take a wrong decision.

First of all, your ex is an ex. And it must be a reason, right? I unknown the reasons but you can’t stop her for taking her own decisions. You should guess first if she needs your help or any help. And in case she need it because she’s being abused, you must follow some steps in these cases that is a protocol. She should attend with you or with another person as support to the right place to receive information about the steps to do when someone is being abused. The best in these cases is the safety of the person who is being abused.
Then, in the case of the kids, you can intervene by reporting the abuse but you have to be sure of it.

I’m not diminishing relevance in a serious topic as domestic abuse or questioning the veracity.
What I don’t want is you to take a bad decision.
Said that, I don’t know the whole picture or the context so, I can’t add much more.