Pussycat, your dil certainly has issues. My d cut off both sides of the family, her husband’s and then her own. I was the last, she knew being widowed she might be landed with me, but I have managed. Its been 10 years.
In the circumstances I would just carry on as you are, at least you will see your son and grandchildren. You won't change a self absorbed, bitter person. Try to concentrate on those that do care, like your husband. I know how upsetting it is but it would be far worse if you were out of the picture.
Paddyann, why you think OP is like your sisters mil is a puzzle, why when shes more upset you felt the need to say it even more so and unkind.