Can Cancer/Chemo Make A Person Insane?

My mother was diagnosed with non-Hodgkins lymphoma almost two years ago and underwent 6 months of chemo. She has been declared cancer free(but not cancer cured yet). She was never easy to get along with but now she is impossible. She has become extremely violent. She has tried to push me down a flight of stairs, stab me in the chest with a pair of pruning shears, and twice tried to strangle me. Just now she tried to shove a vacuum cleaner hose into my mouth. She denies all of this and refuses to get help. I would like to leave but she does things like accidentally set the house on fire(twice). She can’t be left alone. My siblings won’t help. They’re just waiting for her to die so they can get their inheritance. No other relatives will help either. In my state you can’t force people to get help. I want to die, it’s so miserable with her. What can I do?
The only medication she is taking is Fosamax for osteoporosis. Nothing like this is listed in the side effects.