I'm sorry this woman is causing this harm in your family. Even you know, though, that narcissists can be powerful in their manipulation. It may not be that be doesnt love you, she's just manipulating him to do her bidding. My brother's wife is very similar. And we all quite liked her at first. Until she kept driving bigger and bigger wedges between him and all of us.

I'm sorry he has treated you and his grandparents and other family so poorly. I hope that somehow he realizes his mistake and apologizes and spends time with yall again.