I would suggest eliminating all contact. By that I mean, if she sits down next to you, say "excuse me," get up and move. Initiate no conversation with her. If, in the course of your work, you must engage her, only do so publicly and about work matters--absolutely no personal chat. You have to frame her actions in public in the position of an aggressor. You also need to document the incidents and put them on file with HR. This is a must because she is senior to you, so if you haven't done so and push comes to shove, you will have no support to fall back on.

You seem to have boundary problems; it's happened before, and you've posted about such issues with friends. I think it's likely that your perception of your actions is skewed. You may think you're being direct, but I suspect you are not being read that way because of your discomfort with confrontation. But in situations like this, you cannot leave any room for interpretation of your actions. And frankly, you have to be extra careful because you have to do more to prove your case against a woman (especially a married woman) than you would have to against a man; it may not be fair, but that's the perception you're up against.

If she's behaved in this manner with others, there should be a record with HR. Don't assume that there isn't; at least in my experience, HR has been extremely careful about confidentiality in these matters. All your efforts should be through HR, outside of your department. Within your department, you must be scrupulous about avoiding engagement with this woman--and you shouldn't act out against her in any way. If you do so, I can almost guarantee it will be turned back against you at some point. She has the power of her position and seems practiced in using it. You have to be above reproach.

If this woman is as unbalanced and calculating in her behavior as you've portrayed her to be, then you need to start viewing her as a predator and act accordingly. If you haven't already, you also need to be cultivating at least one powerful senior ally who you make aware of your achievements (not confide in about this issue) to be in your corner when issues of promotion come up, to counter any retaliation she tries to enact.

The reason to take this to HR and to keep it out of department politics is because the less you make of the issue in house, the more crazy this woman will appear if she chooses to continue or escalate her behavior. Your only leverage in this situation, because she is senior, is the public face of you being the consummate professional who is not engaged with her. If you continue to engage with her as you have, and it becomes a public struggle between competing interpretations of actions and intentions, being senior, she will win that competition. She's tenured so a much bigger hassle for the Univ to deal with; you are expendable, and Univs will choose the path of least resistance in these matters.