Dylan, thanks for sharing your experiences on this. I think it's pretty helpful on quite a few levels. Especially in the specifics, which were not just similar, but oddly so. It's made me see that these people all share something in common, and if others can see that, it makes being objective about them that much easier.
"The result: my mother and my grandmother's reactions proved I was right."
Ironically, your grandmother and mother's reactions do nothing to defend themselves; they only go to confirm what has been said about malignant narcissist's tendency to downplay their actions, shift responsibility, and play the victim card (among many other things...). What's that saying about not interrupting one's enemy when they are defeating themselves?
Happy new year.