How to really move on from my ex boyfriend?

Hi all,
I’ve recently come to Fluther to ask for relationship advice.
I feel that having unbiased advice would really help me out during this tough time.
I have been in a long distance relationship that has been on and off again basically since 2009.
We met on MySpace, and instantly, we hit it off.
He lived in NY and I live in CA.
At first we were just friends, due to the fact that he was 18/19 and I was about 16.
Over time we had grown a close bond, we would talk all the time, mostly text and phone calls, my ex boyfriend suffers from bad anxiety and I was really there to give him someone to lean on.
Eventually we had went our seperate ways and he had went on to have a girlfriend, and they had a baby and had gotten married out of wedlock.
I had had a boyfriend, finished high school and went on about my life.
At points, my ex boyfriend and I would talk, and I could tell at times he wanted to be together, (I sort of wanted to be together, too.) but I had a boyfriend during those times and he was still with the girl he had a child with, so I honestly felt it wasn’t right to be together.
Last year, around March, my ex boyfriend messaged me on MySpace. (I know, I’m surprised I even still check that inbox…)
And he had just honestly said, “Text me, (—-)—-——I miss you so much.”
I had to sit on this message for at least about a month before I made the choice to pursue this.
I had finally gotten into contact with my ex, and he had to explained to me that he was moving out of his ex wife’s house and getting a divorce. At the time, I was just hoping it he was okay, because I know this is a hard situation.
Going forward, we had planned meet each other in the summer for the first time and see how things would go.
We met and everything was wonderful.
I planned on eventually moving in with him and starting our lives together. I felt that this was going on a little too fast, but for some reason, I felt that this was a risk that I had to take.
Before I planned to move over there, my ex boyfriend had convinced me to get a cellphone for him under my name. (Big mistake.)
At first it was really cool, we both had iMessage, we would facetime, etc.
But then I noticed there was a weird spike in text messages and minute usage, so then I looked into this and discovered, my ex had been talking to a girl he met in a gaming chat room and this bothered me a lot.
So, we talked about it and he agreed to not talk to her, and it was a bump in the road for us so to speak.
As time got close to me moving there with him, I realized I needed a little more time to save money, my plan was to completely pay off my credit card and cellphone bill before I went over there to be with my ex so I could just go to school full time and give my ex my financial aid money if I were able to get it and look for a small job in the mean time.
My ex was really mad about this and said that I didn’t really care for him and that I had lied to him and that really hurt me because I did care for him and wanted to be there for him.
I had went out to see him, made the choice to move out there and be the best girlfriend I could be.
We had still hung on to each other for awhile, I assume because we were comfortable.
After awhile, we started to argue because he has a problem with self medicating his anxiety, etc with alcohol and I honestly tried to steer him on the right path, and he took it as an attack.
I realize at this point, you can’t change someone who doesn’t want to change or admit that they have a problem, but love is so blind; as cheesy as that sounds…
During this time, he has distanced himself immensely from me, because he feels that I am a ticking time bomb, and I admit that I have had my melt downs…
I am still paying for his phone bill and I notice that he had started talking to the girl from the chat room and that really hurt me after the promise he made, so I had confronted the girl and told her the truth which was, my ex boyfriend and I are going through a rough time/break up and he is lying about his name and other information, so I just felt that it was better for the girl to back off.
My ex was so mad that I had confronted the girl and went to his little sister’s friend for sympathy and at this point, I wanted to see if I could even fix this broken relationship and put the cellphone I had gotten him, put in his name.
We are still fighting and at this point it is evident that we will never be together again, but I want to know if there is a way that I can find closure for myself.
When I call or text him, there’s an 80% chance he won’t answer, and the main topic of discussion is putting the phone in his name and he just avoids me.
I just don’t know what I need to do to move on, or why this came to be.
Right now it just seems like a 500$ mistake and talking to a brick wall.

Thank you.