In the end, you must take care of you. These kinds of relationships erode self-esteem. You are still aware enough to know its wrong. Insist on counselling. Demand to be treated with respect. If he won't acknowledge the problem then I'd suggest that *you* leave.
Smackie is right about the kids learning from him. Is this the example you want your kids to have on how two adults should treat each other? Wakeup's comment is just brilliant: you don't need to live together to 'be married' which is largely co-parenting, far as I can tell. You'll be less stressed if you do this and the kids will benefit from it.
Good luck. Its not an easy road, but unbalanced marriages like this rarely are.
Second thoughts can generally be amended with judicious action; injudicious actions can seldom be recovered with second thoughts.
--Cyteen by C.J.Cherryh