You can't please everyone. Don't try to. (((hugs)))

You don't tell her you don't want to see her. You also don't have to go see your mom.
You ARE an adult, and you don't have to play by the family rules anymore, you can have your own rules. Things like enjoying the holidays with people you do like.

If the only reason you're going is out of ... or.. wait, why are you going???