Spinner--in all seriousness, I think it would be best to get her a gift that she might, as a woman like. Say, perfume, a pretty scarf, etc..........
I understand the bitterness and anger, well enough.
In the final analysis, we need to keep our side of the street clean. Considering the message of Christmas---treating her with dignity would seem to be the high road. She is a person--even though she is sick. Your children will be watching---and they love their mother, no matter what. If you insult their mother--you will insult them. They will carry these memories with them. I am sure that you would want them to remember that you also had compassion.
Actually, I have a feeling that this is what you will do anyway....after the joking around is over.
(I do understand your bitterness, though)
dandylion