What do I do when I am still very much in love with my ex?

This is a long one, but please read the whole thing and respond because understand that I really need advice. Please you guys.

I am 19 years old and my ex boyfriend is 20. We were together for exactly a year and a half and were very much in love. I can honestly say that he was the first man I have ever been in love with. Although our relationship lasted for quite some time, it was never without its problems. We argued over everything…literally. And out fights were bad, to the point where there was yelling and screaming and cussing and slamming doors. But regardless, we always pushed through because we knew how we both felt about each other. It took me a long time to admit that I truly loved him…we broke up for 2 weeks about a year into the relationship because he didn’t believe that I truly loved him and he thought I had been just playing him for the past year. So I realized then that I really did love him…and I fought for him harder than I ever thought I could fight for someone.

We got back together and for the next 6 months or so all was well between us. We had our fights and our issues, but what relationship doesn’t have fights and issues, right?

Then, suddenly, out of the complete blue, (and I mean the complete blue) he told me that he still loved me but he couldn’t be in a relationship with me anymore. He said that we had too many differences and problems that he just couldn’t deal with anymore. I was dumbfounded confused and heartbroken because I honestly really am in love with him, and I couldnt see how a person’s attitude could totally change like that in not even a 12 hour period.

I left his house in tears and didnt talk to him for the rest of the day. Then that night, at like 10:00 he calls me telling me to come over. I, ecsatic, immediately hop in my car and drive to his house. The second I got there, he covered me in kisses, told me he loved me, and we had sex. I didn’t ask any questions, I was just so happy thinking that he had changed his mind about us breaking up. But as soon as it was over, he became withdrawn from me. When I tried to confront him about it he only got irritated and snapped at me. I was so confused. I asked him where we stood as a couple and he responded with, “I told you earlier today where we stood.” I started to cry and asked him what this had meant, with him asking me to come over. And basically he told me that nothing had changed and he still couldn’t bring himself to be in a relationship with me. I’ve’e never laid so close to somone yet felt so incredibley far away.

The next day, I wrote him on im and told him that I was in love with him still and that I didnt want just half of him. But since he didnt want a relationship I didnt want to see him again anytime soon because I needed time to heal. He got really upset, wrote “fine leave me alone then!!” in huge letters and signed off.

That was a little over a week ago and is the last time we’ve spoken. I’m hurting so bad because I love him so much. We discussed marraige, children, we were going to move into an apartment together , and he gave me a promise ring that we very much treated like an engagement ring. He introduced me as his fiancee for god sake, and when we looked at engagement rings together, he was more excited to take me to the jewlerer than I was to go!

I just don’t know what to do. I am so in love with him and heartsick. Is it right to not talk to him anymore? Should I stay his friend (which he wants us to be), or am I doing the right thing by cutting him out completely? I just honestly don’t know. I wish I didn’t love him like I do.