This money is CHILD SUPPORT and was paid by your XH for benefit of his children, and you were only the legal agent for it. Your (I can barely call him this) husband, had nothing to do with it, and his taking it early on, (before you kept quiet about it) is stealing. He, not you, is the thief.
Thank God, you must have had an inner knowledge of trouble coming, and have taken some precautions just in case. Now finish the job.
Change accounts at your bank, even change banks if you must.
Have this ignorant, brutal bully charged on every count the cops can charge him with, and do not let him talk you round to letting him get away with his violent actions. Please point out to cops that you had to hide the support money as he had taken it before. Maybe he can be done for theft as well.
You supported the family financially as well as coping with caring for this mongrel, the children and the housework......did he do any housework as soon as he got home from work? SLAVERY HAS BEEN ABOLISHED.
The only error you made, was staying with him after he hit you and not leaving him to play his games on his own. You and your children are safe.
I am now in the right mood to tear down some old paling fence, by imagining it is this wacko I am pulling to bits. Wonderful therapy.
God bless