We had a similar situation at my work, a girl started seemed really nice, then went for a drink with my boyfriend and slagged us all of including me. A lot of the things she said was either the wrong perception or she was just plain making things up. Fortunately she was a known drama queen, so it held no water. She was also the typ of person to go to one colleague make something up, then go to the other and tell them something else about the other person. Everyone tried to be nice, and put it down to trying to find a way into a tight team. After a couple of months of it though, noone was prepared to talk to her about anything other than work related. She handed in her notice, and when asked why? She replied it was because we were all bitchy but then got the response from the boss, that maybe she should think about these things before she goes running off to tell staffs family members lies etc etc and shouldnt act the same way in her next job.
I wouldnt take it personally. Some people are just like it. Dont mingle with her, just do what you have to to get by, but dont put yourself in a position where she can say you have been bullying her.