I'm a 19 year old female.  When I was younger I went out with this guy that I really liked.  I ended up breaking up with him and stopped talking to him 2 years ago.  I got an email from him a few weeks ago and we have been in touch.  He is flirting with me, so I assumed that he had feelings for me still.  I thought 'great, maybe we could get back together'.  My best friend and I are very close.  She has been asking for my advice on a guy named Mark that she's been going out with.  So, as her friend, I gave her advice and sympathy for her situation.  When I was talking with my ex, he let it slip that him and my best friend have been going out fo some time now.  She didn't want to tell me, because I might be mad.  Needless to say, I'm fuming.  Also, Mark doesn't exist.  It's just my ex by another name so that she can talk about him without telling me.  To add insult to injury, he asked me what she had said about him.  I had promised not to tell my best friend I know about their relationship, but now I just want to scream at her.  Please help!