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I am sorry that you suffered this abuse as a child. No child deserved that. You are in charge now and are the adult that has to protect your children. You do not have to put up with abuse, relative or not. If he does not stop then I would distance yourself from him the best you can. Do not let him control your life anymore.
I would suggest you see a therapist to help you work through this difficult time in your life. They will help you deal with what happened as a child and will help you learn to set your boundaries with him and your family.
I hope this helps. Please let me know if I can assist anymore. I am here to help.