Live rent-free in their heads
Leave it there. Draw a line in the sand. Don’t go any further. When people try to get you down, or try to push your buttons, you have a choice. But often that choice isn’t really a ‘choice’. Often that ‘choice’ is to leave it there. It’s to move away and move on. That way the person trying to get into your head has nothing to go on. You are living rent-free in their head, and it’s their problem, not yours.