Originally Posted by Rain Man
This is a good point. If you go, he'll be more uncomfortable and insecure than you will be. You win just by showing up and not talking to him.
The point about the kids is valid, so if you don't want your kids to see the discomfort, just go on your own and do their Thanksgiving at home. Two turkeys never killed anybody unless someone has a hunting story that I haven't heard.
I've been waiting and reading before I responded just to clear up my feelings, and this is it. I think by not going you're pushing her closer to him.
Good luck to you and your mom, whichever route you travel.