What did I do wrong In this situation?

Hi.....I really want my ex boyfriend back but he treats me like I dont exist. It's really starting to get to me. U see we started off as friends nothing more he had a crush on me ever since we were in the 4th grade. Some odd and crazy things happen in my life and he always seem to be there. The only thing is he got a girlfriend and they went together for 3 years......Now dont get me wrong I didnt try to break them up EVER. I really liked her she was cool. The thing is I back off and went my seperate way until last summer I came back around. Now heres the thing he hit rock bottom right after the summer he had no job no car no money at all PERIOD!!! His girlfriend basically started going to other guys for attention and his friends well disappered cuz he was always sad. So I didnt mind being there for him. So his mom made him join the army either that or get out....I drove him over 40 miles to the recruiter everyday almost. Then in Feb. he got into the army....in march at basic she called tellin him I just wanna have fun and broke up with him.....He was about to go crazy so I wrote to him EVERY SINGLE day...He wrote in his letters for me not to leave him becuz he knows I got his back....During his graduation me and his mother was the only ppl to go at all. So the last night we were about to eave he started to cry (sounds gay but true) he told me how much he loved me and how he wanted us to be together...I asked he so many times was he sure and I asked him was he truly over her he looked me dead in the eye and said I swear to god on my moher I am...So we got together...As soon as he got to A.I.T what do u know she popped back up...I told him I didnt like them being so close he got angry and said I was actin crazy so I ended it not even two days he got back with her....Now he doesnt have time for me he curses me out on a regular he always angry he blames EVERYTHING on me. Yesterday we had an arguement he showed her everything and she made a facebook stat about me begging him and I looked stupid smh...I asked did he love me and he said NO!! and blocked me from facebook.....I feel like she has won and she didnt do anything but leave him...You guys I feel hurt and used what should I do money really changed him..my friends are his friends so they are sayin just leave him alone he will come around and apologize.....What should I do deep down I still do love him and I wanna be back with him but he has some serious changes to make.....PLEASE HELP HAS THIS HAPPEN TO ANYONE BEFORE(Im not yellin either just in all caps) Now I have to watch them on facebook be all happy couple together....He wrote me all kindof letters saying dont leave him...Im all he had..smh