Thank you both for your replies.

Echoes, I am seriously out of my depth now - I sometimes believe she is being manipulative and then I sometimes believe it's me being manipulative. I feel like I have genuinely lost the ability to work out what is real in this interaction. My head is spinning. One minute I think you are right, it is purely twisting the knife where it hurts most, and in the next beat I think with utter clarity that she is right. And that it hurts so much because she is right and I just have to face up to it. That all the other stuff is a defense on my part against facing stuff. But then I think of some of the mad stuff she's done/ said and I spin round again and...well, you get the picture.

Just Shakey - I am so sorry for triggering awful memories in you. Truly I am. I don't think I would feel hurt if I walked away, what bothers me most is I can't work out if I'm doing that to avoid confronting my own awful behaviour. That's where it's different from your case - I have a pattern of pushing people (unwittingly, but happens nonetheless) and they pull away from me then. I am not innocent here. I demanded and demanded and demanded and could not accept the new boundary structure.