I've seen more sister fights than you can imagine. Sisters should stay away from each other. The one brutal selfish sister will attack the other for dominance or control and before they realize it the whole thing turns into a bloodbath. After the fight the sisterhood thing is all over. There is no reconciliation possible. Total separation is the outcome. Go to a lawyer and get family divorce papers drawn up. Change names for real. Move to another state. Quit talking, quit the family reunions. Get away from the monster in your life forever.