Bad parent

So, my mom has always been on drugs for as long as I can remember. She's not only physically but mentally abusive. She kicked me out about a year ago for calling the cops on her when she choked and punched my little sister. Recently, she kicked my little sister out (she's 15) and called the cops on me for letting her stay here with me. What should I do? I have two other little brothers who live with her and I'm scared for their saftey. I already called the cops and cys. They're doing nothing. I need help desperately!!!