I am new to this

I met this woman on a dating site. I should have know it was a bad idea considering how fast she was to move things to the bedroom. But like an idiot I was ok with that. In short order my feelings for her started to grow into love and she said that she loved me too. she was in a much different place than I was since she had been divorced for a few years and already been through a few relationships. I was texting her a month or so after we began seeing one another and she said that she was on a date! I was pissed! So the next day we met for lunch and she said that we never had the discussion about being exclusive but that she was not opposed to the idea. So we began what I thought was a real relationship. Things were going well in the beginning. LOTS of sex and emotions and spending all of our time together. Phone calls on the way to work, lunch every day and things that normal people do when in a relationship. As time went by I started noticing things that now I realize were huge but at the time I made excuses for. I sent her a text last mothers day and she asked me why? She said "Im not your mother"! And a host of other things but I will spare you most of the details. I'm in the military and she worked on the base. But her attitude towards us was unbelievable. She has no respect for what we do, stating that we knew what we were getting into. And that it was just like any other job. I agree to a certain extent but dam! So I was at her house, cutting her grass while she was visiting her parents when a woman walked up to me with a fist full of emails. They were between my girlfriend and HER HUSBAND!!! She had been on Craigslist and exchanging emails with this woman's husband about getting together for a hook up. On mothers day my girlfriend, Robin, was asking him if he could sneak away for a quickie! They only lived a mile apart. But he said that he was cooking for his wife so he couldn't get away!!!! When she returned I held it all in. Why I don't know. But we went for a bike ride and she took us down a road that we NEVER went down before. I remembered from the emails that he lived by the library. WHERE WE WERE RIDING PAST! A couple of days later she could tell something was up so when she asked what was wrong I asked why she had taken us down that road. She played it off and that's when I confronted her. She apologized and said it was for masturbating purposes. I should have walked then but I didn't. Then, just before a trip we had planned, she broke up with me. I was devastated. After a month or so of me begging her to take me back, she did. We soon made plans to move to Washington DC together. I took orders and she was going to follow when she got a job here. So I found a place to live and she moved up shortly after with her new job. On day one she borrowed my phone to look up the rental truck address so we could return the truck. She was actually going through my emails. She found one in particular where I was turning down another woman's advances. I told the other woman that I was in a relationship and that while I valued her friendship, "WE" were never going to be because I loved my girlfriend. She blew a gasket. At that point i couldn't take anymore. So I stuck to my guns. If you read an email where I was turning down the advances of another woman and are still mad? Then so be it. We're done. Needless to say she relented and we carried on our lives together. Then the honey moon phase ended and we started the mundane existence of daily life. At first things were good but apparently I lost that new car smell. She began fishing for compliments and talking about what other men were saying to her. In typical guy fashion I wasn't getting it. So she left her phone in my car one day and the next morning on the way to work she got a text. I didn't know where it came from so I searched for the sound and found her phone. It was a text from an old lover telling her he had a great time the week before she went to NC to visit her daughter and couldn't wait to do it again. So I dug deeper and found more texts from other former lovers. I went off on her and she apologized and blamed it on me and my lack of sex drive and what not. I was still trying to get over the first time she was sexting a guy so give me a break. Anyways, I caught her yet again through texts when she went out with another guy while I was out of town. That's where it ended. We have a lease for another 4 months and I don't think I can go on living in this house. She's on Match.com, she doesn't know I know, and still trying to compliment me so that I will be her other source of supply when she wants me. It's just one mixed message after another. This past weekend she called me on Friday and conveniently her daughter called and she said she would call me back. Well she texted me on Sunday afternoon! At that point I was done so I told her I was on an overnight hike with my dog at which she replied asking if I had told anyone my itinerary because if I didn't come back she would be worried. I didn't reply til the next day. I told her that I wasn't alone but that I was fine and off the trail. She immediately went into her old mode. So you have a new hiking buddy? Good for you. By the way I won't be home until real late so don't wait up. She didn't come home until this morning after I left for work. I passed her on the road. Why in this world can't I stop obsessing after this monster????? I need your help desperately! I need to find a way to get over her. I am moving in with a friend but not for another week and a half. I am going to wait til she leaves for work and move out all of my stuff while she is gone. So that when she comes home every part of me will be gone. How pathetic am I? It's like I just want one last shot at pissing her off? I'm a 43 year old combat vet still on active duty and I let myself get upset at these games? What is my problem? How do I get her out of my head? Please HELP!!!