Only your grandmother knows why she reacted that way. She could have been abused as a child and never told anyone. Well your grandma is a standup person that will not tolerate abuse. Too many times victims are stigmatized and even intimidated not to talk by their abusers. Other victims are not believed.

It is not the victims fault that they are acting like a victim. It is the abuser's fault. But for healing now the best thing could be to move on with a therapist that specializes in surviving abuse.