R.V.
M.,
If you plan to stay in this situation then you need to be prepared to call the police when he gets violent.
His Family is just that "his" and they will not support nor help you they will always do what is best for him.
I would no longer have anything to do with his family after the way they behaved toward you, I would not be around any of them.
You need to have an emergency fund that only you know about and when you need to get out you and the kids can go to a hotel.
Good Luck