On Mumsnet, the happiness of the people you love the most is "not your responsibility," you have no obligation to invite an elderly lone parent for Christmas, and if your husband turns out to be a human being instead of a perfect robot, LTB!!! As for extended family, they might as well be strangers. How do you not know this!! 🤪
Oh - and once you marry and have kids, your parents and siblings are extended family.
And if your mother won't look after your kids, it's perfectly reasonable not to let her see them. She may be upset, but her happiness is not your responsibility!!!!