For some people I make my boundaries invisible so they don't get much feedback from me. That way it's harder to use you because they don't know if you mind or don't mind. Pushing people's buttons and having them not react can be very disconcerting I've heard, LOL. Schadenfreude is fine, since it's all in your head, no need to feel guilt for it and/or you can pay by "withholding" yourself when you'd like to explode all over her when she pushes your buttons. Invisible your buttons and she can't deliberately push them, can only "accidentally" push them when she's ill but not get any satisfaction over doing so.