If you have a cutthroat, backstabbing coworker who’s trashing you to your boss and colleagues, it’s never fun. But it’s also not impossible to deal with, either. Instead of being reactive–which is exactly what the jerky worker wants–be proactive and take steps to protect yourself.
You want to be able to potentially prove a case later, and if she says you did X, Y and Z, you’ll want proof that you actually did A, B and C. Write down every time she fibs about you as well so if push comes to shove, you can refute them and show how she wasted her own time and productivity by trashing you.
Meet with your boss regularly.
Ask politely and kindly what you need to do to improve your performance and see what she says. If your boss doesn’t bring up any issues that your conniving coworker has lied about, chances are the smack talk either isn’t moving that far up or that your boss is dismissing it for just what it is: smack talk. Not only will you gain insight on your situation, but you’ll also develop a rapport with your manager, and that can only help you.
Confront your coworker directly and end on a positive note.
You don’t want to get into a screaming match–that’s what she wants. You do, however, want to calmly let her know, “I know you are saying things about me that are not true. I have been documenting these incidents and promise to report any attempts at slandering me or my work. I want to have a good relationship with you. How can we make things happier around here? Aside from not wearing pants, obviously.” She’ll probably deny it or get defensive, but whatever–not your problem. You just did your job.