I think there is a ridiculous amount of judginess on this thread and a remarkable lack of empathy.
OP your mother sounds a PITA and an emotional blackmailer to boot.
I personally find it very patronising to the elderly that people are saying Awww she's 80 and a widow, suck it up.
So being a senior citizen and no longer in possession of a husband gives you special status and the right to act in a demanding and passive aggressive way? As if you're no longer a normal member of society but need to be treated with kid gloves and condescension?
And all those people saying she wiped your bum and cleaned your teeth... Firstly, presuming much are we, how the feck do you know? For all you know OPs Mum might have been neglectful [and in fact OP feels her mother has NPD which in all likelihood made her emotionally quite neglectful of others]. Secondly, so the hell what? That's what mothers do, wipe bums and clean teeth, etc. I sure as hell don't expect my DSs to be grateful for this. I chose to have children and I knew that I would be required to look after them. I don't think an elderly parent automatically deserves this same care, particularly if they are not particularly pleasant to their offspring.
OP only you can decide whether you can live with the fact of not inviting your mother for Christmas and her emotional manipulations if this happens.
Personally I would not give in to her demands and would have a quiet Christmas with your family and invite her for the New Year instead.
I mean if DM makes Christmas so stressful isn't it a little unfair on your DC? Christmas is really a celebration for children imo and should be about them and making lovely memories for them, not difficult and demanding elderly family members.