I have been catching up on your situation and I am so sorry you are going through this. It is so traumatic and please, don't look back and beat yourself up for not correctly implementing DB techniques...hindsight is 20/20 and your responses and emotions were pretty normal considering the situation.
Look at the here and now. Truth be said, your husband was acting like a child that has never had to deal with real consequences for his actions. Just like raising children, you can't back down on your word or they will walk all over you. No matter how much we love them and want to give in, it does no one any good and then the bad behavior continues. Think long term right now.
im just one poster out there, but I think based on his history he has to hit rock bottom and truly be remorseful or else what's to say this does not just happen again when the next crazy pos comes along. Btw you have great insight when it comes to her.
Your anger, your yelling, your rage will not change him. He is the only one that can do that. The only power you have is to choose whether you want to stay and deal or leave. And that is a lot of power. You don't have to accept this. That's what detaching and NC is about.
I think right now you need to be extremely selfish. Do whatever it is that makes you happy. Do not even consider him (this is what I'm trying to do as well. I know easier said then done). Make it about you and your needs. Take your time. Give him time to fix it. You may or may not be around by the time he does.
Me: 42 H: 43 Twins age 5 Physically Separated 7/2015
