Hey, Bodhi,
Sounds like you have a good plan for escape when the going gets ugly, that’s always been my strategy, too. Sounds like your in laws have a very unsavory relationship with alcohol and either don’t know or care just yet. I bet they will down the road, and they are likely to come to you. Do what you need for you, we get to be selfish for the right reasons now. I give you a lot of credit, I wouldn’t be as considerate and I would be skipping the holidays!