Sounds like pathological lying coupled with some histrionic behavior. Not exactly my field, but your "friend" needs to see a therapist. Sounds like a possibility for Histrionic Personality Disorder.
If you think she's worth it, or if she shows signs of guilt for her actions, I do highly suggest you try and talk her into seeing a therapist. Pretending to be raped and trying to continue the charade is a VERY serious sign of a mental problem when you consider the severity of the crime she pretends to have suffered from, not to mention the almost irreparable harm she can do with a false accusation to her supposed assailant.
The irony here is that in the end, she's the one who's going to suffer the most from her actions and not you or your other friends. As I've said if you think she's worth it, and if you really want to help her, try to get her to see a specialist.
If she refuses or you see no way to try and make her change for the better, then it is time to cut off all contact from this person. Her refusal to change will ultimately drag her down into the gutter, and if she continues her slide into her own personal hell, then it would be wise not to be dragged down with her. Sorry to say, but in the end that might be your best option.
Good luck with this.
