Hi WhiteClouds ~ There is a saying that I try to remember in times like this. It is: "
Resentment is the poison I take to kill you." When we continue to resent someone, all we're doing is killing ourselves. They don't know we're resenting them! They don't have a clue we're carrying this resentment around!

So we're eating our insides out, while they're just going about their normal business! Darn it ! LOL
You have been so very thoughtful for their side of the family. It seems very cruel of them to ignore the fact that your Grandfather died. What did your husband say about this? Didn't he SAY anything to his parents or remind them that your grandfather had died? He should have said something. Regardless, they should have acknowledged it, and I don't blame you for being angry.
But try to let this go, not for THEIR sake but for yours. Carrying this resentment around is going to make you sick both mentally and physically. It's just not worth it and THEY aren't worth it. Be the bigger person and continue to acknowledge close family relations who pass away. Don't stoop to their level.
I wish you the very best. God bless and PLEASE take care of YOU. Hugs, Lee