In desperate need of advice

I am currently in a situation with my family that I don't know how to handle. My mother is great, but she is constantly forcing my brother on my husband and I. He has always been very hateful and violent towards both of us (threatening to put me in the hospital as well as my husband.) Recently, my brother told my father, who I have not spoken to in 7 years, that I am pregnant. This hurt very much and when mentioned to my mother she made excuses for my brother and even asked if I was sure it was him... and said she would handle things. I said no! I am tired of being treated like a child, i'm 26yrs old and my husband is 30. She see's our arguments as squabbles between two children and I am really starting to resent her for that. She's forced my brother into going to things that my husband and I have planned because she doesn't want him to feel left out, and when he goes we are treated terribly.. How do I stand my ground without breaking her heart or her blowing up on me? I have confronted her about it before but nothing changed.