What is a girl to do?

My boyfriend and I have been dating for about three years. Our relationship started out rocky due to the both of us having unresolved relationships with our ex's. Unfortunately there was lots of back and forth with the ex's especially on his end. These incidences put lots of stress on our now existing relationship. Last summer we moved in together, where I found out he was STILL talking with his ex! This started one of the biggest fights we had ever gotten into. He took off to Texas for work the next day and left me in Maine. We tried keeping the relationship going, but it got to the point that he was ignoring my calls all day until he was in bed getting ready to go to sleep, we were fighting still, and he would break up with me every other week. While this was going on a guy at work asked me for my number to take me out sometime. I accepted and gave him my number. We ended up sleeping together, but nothing more. We never dated, we never were exclusive, I really only liked him because he cared about what I said and was sensitive to my issues (unlike Mr."Boyfriend" in Texas). Well my boyfriend came back from Texas found out about the guy at work and started hanging out with him ex (AGAIN!) Eventually we started dating again but it was rough. When I say rough, that is a complete understatement! Fights we had before seemed like love and we got to the point of shoving. Everyday I was crying harder then I've ever cried in my entire life. Our fights exhausted me because I had worked so hard to make it work with him and to know that three years later all of it literally meant nothing. We decided to move out of state together (for his work), thinking that location would be the key to making us work. Unfortunately things don't work that easy. We still fight, I still cry, he still doesn't give me respect or listen. He is very involved in himself, ignores me even when we are getting along. I feel as though he just doesn't care anymore for the most part. Every once in a while we have a good day, and it's these days that keep me holding on to hope through out the other days. I can't seem to let him go. The thought of him moving on, being with another girl, me going back home thinking about him, all the memories, and things we've done together, all the work, time , emotions, and love I've put into us. I just can't handle the thought of leaving him. If anyone has any insight on what I should do. How to get him to listen, or care again? How to deal with our horrible past? How to be numb to his out burst? How to not feel so sad and hopeless? Please somebody! Help!