Going to a funeral with my wife. How do I keep calm with her crazy family?

My wife’s grandmother died and we are going to a funeral Saturday. Her whole family will be there and let’s just say I can’t stand them. They are a bunch of druggies who only care about themselves. My wife’s childhood was ruined because of everyone in her family. She was molested by a couple of them and my wife still at the age of 33 has serious issues and ptsd because of it. I just need help lol. Please someone give me advice on how to keep my cool. How should I prepare myself for this?