I find it astounding that you emerged from this familial horror and betrayal as an intact person able to reflect on your experience and even express compassion for your mother. I am so sorry you had to sustain these deep psychic wounds, but it sounds as though you will not be unconsciously passing their pain on, as your family has. I do hope you allow yourself to stay away from your grandmother: nothing obligates you to expose yourself to her toxins, and your healing is more important than trying to make an impossible peace with her.