You are more than trying, and there is no excuse for them to completely ignore your BEAUTIFUL boys (and they are!!!). Honestly? If you always get burned, why even go over there? Who cares if they are "family"? It sounds like you would have a much better (and more peaceful) Christmas without them... maybe you should just spend it with DH and your boys. TBH, I am 100% happy just being with my kids and DH, and it sounds like you would be too, ESP if they are being such sh*ts to you and your kids.
I agree with this completely! Enjoy your Christmas without having to feel like an outcast! If it pisses them off, so be it.
I am sorry but your MIL sounds like a cow! How insensitive! Great if she has a granddaughter but she has grandsons too! Has your MIL by any chance GD??? Is your SIL her daughter? Or her Daughter in law?
Dont go there for Christmas have a nice Christmas at home with the people who care about you!