@StillNiceCardiganStick to your guns! I had several months at this time last year of emotional blackmail (see user name!) trying to get me to go and have Christmas at “D”M’s house, involving dragging my family there along with the food, then me doing all the cooking but in a kitchen that isn’t mine, plus providing entertainment for endless people dropping in so she could show off her helpful daughter.
I stuck to our plans - she was invited to ours for Christmas but came up with every excuse under the sun not to come. A younger less determined me would have given in, but I wasn’t going to ruin my children’s Christmas. It got to the week before Christmas and she did a lot of flouncing about how she’d have to spend Christmas on her own. (Her choice if so!).
We had a blissful Christmas with just us there, and eventually saw her in January. She spent Christmas Day with a friend. She was really annoyed about waiting for January but by then we’d made plans with other relatives and friends so she just had to fit in with that.
Good luck! It is so hard when they’re behaving like this.