Assaulting a child is completely unacceptable. If you do not take action it will get worse.
You appear to need some serious help, so call 1-800-4ACHILD if in the U.S.A., or Childline (0800 1111) in the U.K. No doubt other countries have similar free phone lines. Canada is 1-800-668-6868, Ireland:
https://www.childline.ie/.