Sola, I'm so sorry you'll be alone on Christmas. (((Hugs))) I hope you come back in and answer the questions GNers have asked you to round out the picture. It's not clear whether DS and DIL always do this to you or are alternating holidays or what.
Like PPs, it would be hard for me to leave someone alone on Christmas. However, if it his ILs "turn" to have him and DIL, this year, and if they're the hosts, he can't very well force them to invite you. If they're the kind who only want their own family members or if there are tensions between you and them, then they really might not see it as a good idea. If I were his MIL, I would probably have invited you. DEFINITELY IF I knew you would be alone otherwise. But not everybody is like that, of course.
SrWendy - So there are two of us - Wendys, I mean! LOL!
But my heart goes out to you on the passing of your DH and your DDs. How tragic to lose even one child, let alone more than one. So deeply sorry.
Glad that your DS' ILs are including you in Christmas this year. Hopefully, it all goes well and will, as a result, happen again.
My heart is with everyone here who will be alone tomorrow and Friday. I hope you find enjoyable things to do, treat yourself to a delicious meal and/or indulge your choice to eat our of the can, and, perhaps, find some fun and solace by joining other GNers here.