I guess just let her be her & don't fall in her trap. Don't accept anything from her. Don't do anything. You can't change her but you can change how you react to her. Even if that reaction is ignoring. I know this isn't good advice but it's how I handle situations. I just don't have contact w/ people that hurt me then they won't continue to hurt me.
I hope you're taking care of yourself. Big hugs to you.
Love,
RhysMadison