Do I have the right to defend myself from these attacks?

[Cowboy'sSweetheart]

My mother has Alzheimer's. She has become extremely violent. She refuses to take medication and under the law in this state she cannot be forced to. She also cannot be put in a home against her will. In the last year she has tried to push me down a flight of stairs(twice), stab me in the chest with pruning shears, attack me with an electric saw(it was running). I've lost track of the number of times she has sneaked up behind me and tried to strangle me. I have bald spots from where she has pulled my hair out. My siblings won't help and the police say there's nothing they can do until she hurts, "a member of the public"(guess I don't count). I'm afraid if I defend myself she will get hurt. But I am becoming more and more afraid she will kill me if I don't. I live in Virginia. Am I allowed to defend myself?