An 800-year-old source on distancing yourself, and the honor obligation that survives even that.
Q. How should an adult act towards his parents who abuse him emotionally, psychologically, and/or physically?
Your question was addressed 800 years ago by R. Yehuda HaChasid (Sefer Chasidim, 343). He writes that if parents make it unpleasant for the adult child, it is better for all sides involved for the son to leave home and distance himself. It’s not good for the abusive parent to continuously maltreat, and it’s very difficult for the son to stay passive and not retaliate. You must be careful not to degrade your parents, for even though a parent can forego his honor (“kavod”, Kidushin 32a), the Sha’agat Arye (Turei Aven, see also Sefer Chasidim, 570) points out that they cannot forego “bizayon” (their dishonor, i.e. yir’ah). It is therefore prohibited to abuse them. So instead of degrading your parent, let them know that they leave you no choice but not to visit them. I would suggest trying to continue communicating with them on the condition that they know that as soon as they become abusive, you will need to terminate the conversation. If one parent is not abusive, obviously your connection with them could and should be different. If they don’t want contact with you, it’s unfortunately their problem and absolves you from your obligations. Hopefully this approach may drive home to your parents how much their behavior hurts you, and very well may even improve the situation. BTW, a child is allowed to go to a therapist and discussing the issue is not considered Lashon Hara, especially when the therapist doesn’t know your parents. Remember, the Living Torah is not only moral but also practical, and that’s part of her beauty.