i think i would write her an email telling her to back off and explain how her behavior has been inappropriate--keeping it strictly about work--and then cc it to the personnel dept. make sure she knows it's been cc'ed to personnel i.e. don't blind cc. you aren't reporting her just letting PR know what you have communicated to her, so if she then tries to pull crap at work they will have your email already on file. i would explain/document in this email the incidents where she has inappropriately touched you and crossed your boundaries especially after you asked her not to. this woman is a problem and probably should be fired but i realize that may be difficult if she has tenure. you might even want to consult with a lawyer before doing anything. that would probably be your best course of action really. no matter how you handle this she will likely bad mouth you. sorry to say, but i have experienced that type socially and that is their m.o.

another thing you could do is go to the most senior person in your dept that you really trust and, not naming any names and very briefly explaining the situation, ask for their advice. i think if you try to handle this on your own on just a social level she will bad mouth you like crazy like she did the other woman and it might well affect your job. i think preventing that possibility by either an email or getting dept support and dealing with it professionally is a better way to protect yourself.