What do I do with him, should I just forget about him?

I was seeing this kid for almost 8 months.. We were like bestfriends. We never really got in any serious fights, we got along pretty well and we had a good amount of things in common. Im only 14 years old, but hes 16. Im in 8th grade, and he is in 10th. Hes left me twice, but he comes back to me within the next day or so, but it hurt more each time. The last time he left me, and got back together with me, afterwords, things were going good for a while. We had no problems at all. But then randomly he stopped asking me to hangout, ad stopped calling me and texting me all the time so I knew something was up and I didnt want to be left again, so I left him hoping that he would chase after me. Boy I was wrong. He let me go so easily its like it doesnt even effect him whatsoever. When I ended it with him, I got really mean though. He was like I still wanna be friends.. And I said no, why would I wanna be your friend after you did all this stuff to me? I told him I never wanna speak to him again. And I havent talked to him for about a month and he hasnt even tried to get in contact with me. I know im really young, but me and him were so close we told each other everything I dont understand why he cant let this go so easily. He told me that he was really starting to fall inlove with me and that he worries about me all the time. Even his mom said that during the night when he sleep talks she hears him talking about how much he loves me. Before I came along, he dated this chick named julie and they dated for a pretty long time almost a year and she was his first love, she cheated on him. And I dont know if that has anything to do with why he was acting weird (because he was worried) or what ? I dont even know what to think anymore. He already has a new girlfriend and theyre already laying in his bed and they just started dating, and we just ended like 3 weeks ago. What should I do?I really love him and after all this love stuff is over, all I really miss is the friendship we once shared. Now I cant even talk to him ( I havent talked to him in a month) I miss my bestfriend