Dealing with Abusive Family: Is It Okay to Cut Ties?

Assalamu alaikum. My sister and mother have been physically and emotionally abusive towards me for as long as I can remember. Whenever I tried to seek help, they threatened me. Now, I'm at a stage where I can spend long periods away from home, but I worry about the future. I don't want to be around them anymore because the abuse-hitting, mocking, and insults-is just too much. Talking never works; it only leads to more pain. I'm considering cutting them off completely for my own safety. Is that allowed in my situation?