I have this coworker that is driving me nuts. We used to be on good terms, but then recently she tried to go over my head and behind my back on something that didn't even involve her. Our boss told her I was taking care of a situation and that she should cancel a meeting she was planning.

She had the meeting anyway 2 hours after he told her to cancel it. He then had to talk to her again and tell her to back off.

Today during a group discussion on a controversial target I challenged (in a very appropriate manner) what she said. She claimed we received training on something that we never had. She then proceeded to say that during the meeting in which she says she trained us I yelled at her 1/2 the time. I have never yelled at anyone at work EVER. In fact in this meeting she yelled and cursed at another teacher in a very inappropriate way.

She has a history of sabatoging others and lying or tweaking the truth. While all of my co-workers are well aware of these acts I am not sure our administration has fully caught on yet.

Any advice?