OP, your DIL has created a huge fuss about nothing. There surely are worse GP crimes than taking a child downstairs for a cuddle in the night! Maybe that's annoying to the parents, but the resultant fall-out is so far beyond the crime that I can only conclude that your DIL is selfish and controlling.
It's become the in thing for the middle-aged to cut off their ageing parents, and I think it's a disgusting trend. We've got one like that in our family, and having watched her cause terrible pain to ill and aging seniors, I have strong opinions about it.
I hope all who are so mean to the GPs know what it's like to be on the receiving end of that one day. Yes, ILs can be massively irritating, but the kneejerk response to cut them off is horrendous. GPs are very important to children, and those children won't thank the parents when they're older for keeping their grandparents away from them.
I'm of an age where my parents are gone and where I've seen how quickly people 60-plus can die or develop serious illnesses, and how many people that happens to. I'm sorry they don't value you more, OP. They sound immature and as if they haven't realised some basic truths about life: that it's short and that people are precious, and that you can complain about people's bad points or you can luxuriate in their good ones, and that it's a choice.
I'd stay away for a bit, if I were you. Try to spend time with people who value you more instead of seeing you as a massive pain, as they obviously do right now.