Answer: Although you’ve been frantically searching for an external solution to this problem, the real answer lies within yourself. You’ve given this woman way too much power over you, so you need to figure out how to take that power back. I can guarantee that most people would not let this little tyrant dominate their existence so completely. But for some reason, you are allowing her to control you.
These bullying games always require two players: a persecutor and a victim. If you refuse to take the role of wounded prey, your cruel co-worker’s game will come to a screeching halt. Before you say "that’s impossible," think of people you know who would absolutely refuse to be bullied. Use them as role models, and ask yourself what they would say or do in this situation.
You must also stop obsessing about this warped woman. If you let her command your thoughts, then she really is ruling your life. Constantly remind yourself that she simply is not that important.
Having sought advice from many sources, you must now help yourself by disengaging from this destructive game. But if you can’t, then these interactions are providing some sort of emotional payoff. And that would definitely warrant another conversation with the therapist.