One other thing, with respect to the child support.
When you talk with a lawyer (ideally before you leave), you will learn he is obligated to support the children whether you live with him or not. Actually, you are BOTH financially obligated, but if he's making more money and the kids are with you most of the time, they would be entitled to support from him.
Sounds like you have your work cut out for you, but it WILL give you a feeling of much more control over the situation.