To Thine Own Self Be True
It's hard for me to follow who's who in your story (my fault) but when it comes to holidays and family/friend gatherings why should we punish ourselves?
I have family that can drag me down to the pit of dispair if I let them, I have to leave. I correct them, and then leave (usually about the way they treat the children). That way I don't harbor too many negative feelings on my way out the door.
Now, there is the aspect of selflessness. We can put ourselves out as an act of love for others, but if we do not have a happy heart in doing it, then it is not sincere. It is better to be sincere in all things.
and put that da* cigarette down