Cheated on again

Hello. Last summer my fiance and I broke up for 2.5 months because she cheated on me with a friend. We lived together during this time still and it made me sick. I was anxious, had no confidence, felt unattractive, had insomnia, and of couse was heart broken. While we were broken up I had to sit there and watch her leave knowing she was going out with my friend and most nights didn't come home. I felt so terrible about myself that I made contact with my ex for someone to turn to. Nothing took place between us, but when "Amy" found out she was irrate. Nothing rationalized that I had not pursued another person intimately, only how bad I was for talking to my ex. A couple weeks later we got back together (october 2007). Well, last week (monday) "Amy" snuck into my email and read a message to my brother that I was having second thoughts, cold feet. Everyone gets them. She became extremely irate and left for 18hrs. I have no idea what she did, but she left an hour before I got home from work. The bext message, had she read further, was me telling my brother I was stupid for having second thoughts and that I truely did love her. Since that day she has lied to me about where she's been, has only been home one full evening, the rest she's out til 2am or later. She's contacted and contemplated moving in with her ex-fiance to get space from me, came clean monday that she's "seeing" a guy she met that same monday she hacked my email which is why she's been out late and secretive. Oh, and they've had sex. A couple times. Thursday this week (9 days after her snooping, 3 after telling me what she's doing) she tells me she knows "I'm where she wants to end up" but she doesn't want to break off this thing with "Jerry". She just came home tonight at 3am from "going skating" which ended at 11:30pm. I feel used, and worthless. I know she's playing mind games but it's so hard to pack up and leave. I'm in too deep financially to make it on my own now, thanks to her. I dunno what to do or where to turn...... Tweet