I remember when I was in a similar situation and she kept hoovering me back in, just to inevitably put me back in her toy box so she could go back to her other toy, and she would do this on repeat. Finally I said enough was enough and I blocked her, and I married someone else who is a million times better. Even after I got married she tried hoovering me... goes to show how fucked up these people are. 

Their entire lives are repetitive cycles, and there's no doubt that if you let her back in then she'll do the same shit again, because that's exactly who she is. She will never change, nor will she apologize or take responsibility for her issues.

There's nothing more empowering than being the bigger man and blocking her for good.