There's always at least one doofus (gossip, liar, meanie, manipulator, negative nellie, etc) in every work situation, in my experience. You can choose how you react to that person. That said, sometimes there are so many of them and the place is so effed up that for your own sanity, you have to leave.

You are lucky that you have a relatively "portable" career/specialty. Seems like there are more to in your work environment to make it worth sticking out. YOu might get better benefits elsewhere, given your experience. Listen to and trust your instincts. You'll get yourself to somewhere better....

My last two assignments were nightmares. Eighteen (18) months of dreading having to go to work, being unhappy, & resulting in my seriously considering leaving federal service. Now I've landed in an interesting assignment working for a wonderful boss. I have two coworkers for whose personalities I find annoying (50 year old frat boy who thinks he's a woman magnet & a young female know-it-all w/a chip on her shoulder), but I just limit my contact with them and remind myself that their issues are NOT mine.