Big Hugs to you Heather.
I really hope he gets his head on straight. I know that horrible feeling of wondering how the kids are going to handle all of this, and it is overwhelming at times.
In your case, I truly believe you are doing the right thing. The kids were already in a very unhealthy environment watching their F treat their M so poorly. \:\(
Ideally, you will be able to save the M but only if he changes his own behaviors and takes responsibility for his share of the problems.
I'm crossing my fingers for you.