Guilt is a learned feeling, and we ACoA are great at it. My sister and I have nothing in common. Nothing. Even down to our relationships with our AM. I am No Contact and working recovery in Al-Anon and therapy. She goes on vacation with AM and posts pictures on FB of them at the pool with their drinks. You aren't obligated to make nice with your sister. You aren't obligated to acknowledge her. It gets easier as you go along, and Al-Anon helps a lot with that. Being family doesn't automatically mean you're obligated to go along with the dysfunction.