WTBH,
I really have no advice for you regarding custody as my children were much older when I divorced and my AH wasn't batsh!t crazy. But, I can't help my urge to express concern for your safety. When your AH starts to sense that his plan to destroy you isn't working (and he may already be sensing that), I believe he will ramp it up. There is no way to tell what he is planning next, so please keep far away from him. I fear for your safety and the safety of your children.
L