My parents dont care?

I am 13. And live with just my mom and visit my dad on the wknds. I have an older brother but he moved out a year ago when my mom was still married to an extremely verbally abuseive man who hated me and my brother finally it became to much for my brother and he moved to his dads house (we have the same mom dif. Dads) so anyways he moved out thibgs got worse finally my mom divorced him and now its just me and her. But my brother visits on the weekends and the prob is we are really close in age so we tend to fight a lot. So he'll instigate me and then my mom won't do anything b/c she's afraid he won't want to see her (even tho she's never adnitted it its still totally obvious). Also she has a really bad drinking problem. And she breaks things a lot of things. Plus she is verbally abuseive to me. The reaosn she is this was is b/c her father was to and her momn left when she was 17 plus befoee that she wouldn't stand up for her children . So now wheb my mom is like verbally abuseive my gma won't even help and will lie and twist the storyyy HELP please what should I do thank you