As someone who is also dealing with a difficult family situation, I feel for you. One thing that I ask myself in a search for clarity with these types of relationships is what I would tell a friend or loved one who was in a similar situation. I’d definitely tell my loved one to protect herself by setting boundaries. If it seems that one or more sisters is self-aware enough to stop bullying you, you might tell her that you will see her as long as she does not say cruel things. I would make it clear that any hurtful words or actions will result in your walking away. You do need to protect yourself.