Hi Kat-
I'm so sorry you are going through this. I worked in a very polluted office years ago and I have one piece of very important advice for you (written before but important to stress): document everything and keep every bit of job-related correspondence. Also, demand that there is a witness to any conversations you have with your boss or at least audio tape every conversation or make sure she sees you taking copious notes. It's important that she knows that you're getting everything in writing.
One of the most traumatic things I've ever been through was the result of working in an office with someone who was not well. Shortly after graduating from high school, I had the very unpleasant experience of sitting in a meeting while a co-worker spent 45 minutes reading me a list of ridiculous things she didn't like about me, none of which she could substantiate (I was racist, I stole things from her, sexually harassed the men in the office, lied, etc). It was absolutely horrible and my boss just held her hand and encouraged her to keep going. A few months later we found out that she was bipolar and had gone off her meds without telling anyone. The list she read was actually about her roommate who apparently looked just like me. The night after she read the list, she locked her roommate out of her apartment while she trashed it. She was taken away in a straight jacket. I marvel at the fact that, almost 20 years later, I am still somewhat affected by that experience. No one should ever have to go through something like that. Protect yourself and your future reputation. So glad the folks at HR seem to have your back. Hang in there!
