I live in a student house with a girl called Jess. Last year, Jess liked my housemate Greg. Towards the end of the year it seemed like she had started to go off him and said nothing was going to happen. In the past, meeting someone else helped me move on and I thought that would help her move on even more so I introduced her to my friend Ben who she seemed to really like.
However, she was lying. She never went off Greg and she's just been using Ben for the past 2 months to make Greg jealous which doesn't work because he isn't interested. She just loves the attention of Ben and is playing him.
I really don't know what to do. My friend Anna has confronted her about it but she has just laughed about it. I want to tell him what is going on but I feel this is her responsibility. She just lies her way out of everything and now she's going to break someone else for her own personal gain. I feel so guilty as I didn't think it would pan out like this at all.
I'm thinking of confronting her one last time but giving her an ultimatum to end things nicely or else I'll tell him the truth.
What should I do?