I agree with the commenters that say that is never a hallmark moment o like the movies when the abuser parent "sees the light" and suddenly becomes loving and whatnot, when someone was psicologically or fisically abusive of a child, they know very well what they are doing, and the pain they are causing, when the child comes back as a grown up and confronts them they will have a "justification" (in their eyes), my mother would tell me that I was "evil" (at 5), or that I wouldn't "behave", so at 40 I also decided that I had it, and cut her out of my life and no, I won't feel any regret when she dies, I won't be happy,  she was never in my life with any support or love, so it won't make any difference.