If she's really playing childish games, she wouldn't be trying to contact you. She'd be out f*king another guy. She's trying to have a mature conversation with you. Why not just talk to her and see what she has to say? Acting like an adult means to hear both sides, not rally support to justify that cheating is the worse offense over breaking someone's trust irregardless of your intuition. The more I read the responses (yours and others) to this thread, the more I think this girl deserves more credit and a chance for her to tell her side of the story. Why exactly did she want to cheat, what did you do to give her the reason to? Just something to think about.