Hi L.,
Wow, this is not an easy situation. My first thought is to call the local women's shelter and talk to a counselor. They are trained in this and they also know all the laws about how to get someone out of the house and protection orders. I know it sounds extreme, but it sounds to me that if he is not already it could escalate if your brother does not get his way. This situation is not safe for your mother or your littel sisters.
Has any of your older sisters who no longer live in the home gotten your husbands together to confront him and make him leave?? or tell him to knock it off so to speak??
Your mother, atleast, needs counseling even after he is made to leave and not return (as a visitor) when he can act civilized...
If the women's shelter cannot help you, which they should try the local legal aid they answer questions on the phone sometimes too.
Good Luck and God Bless you all,
S.