I'm with somebody new but I'm growing more feelings again for my e

This is probabaly a situation everyone has heard before… but I still think mine is different…

I’m a junior in HS right now, but when I was going into my freshman year I started talking to this sophomore Carl. We have been together so many different times but he always seems to end it for immature reasons that I never understood, but I was always there– waiting for him to come back, and he did. Until the middle of my sophomore year did we stop being together on and off, but I still recieved drunken phone calls from him, which got my hopes up. He didn’t treat me badly when we were together and I felt perfect when I was with him. The only thing was that he always ended it and I would always take him back. Now being in my junior, he is a senior and leaving by the end of this summer. I feel so much hurt and pain, I don’t want him to leave. We’ve still been able to maintain a good friendship, and recently he has confessed that he still cares about me and he realized how immature he was. He says he likes me and cares about me, and knows that because of his immature doings– we are not together today. He also asked me if we’d ever date in the future… I said I didn’t know. I wanted to say, because I care for him just the same. The only problem is… I have a boyfriend, Joe. My current boyfriend and I have been dating for 9 monthes and he’s a great kid but lately there is no spark or chemistry anymore. I don’t know if it’s just me, but I’ve been losing interest even before Carl shared his feelings with me. I’m just lost in all my feelings of sympathy for Joe because I care about him and I don’t want to break his heart, but also my feelings of lust and care for Carl. Joe will SERIOUSLY never break up with me, he is attached way to much. I don’t know what to do with all this. Carl wants to stay as close as we are now “forever”. (Really good friends, but he is always wondering I think) I want to tell Carl my feelings for him but I think I might just let him down because I’m with Joe, or should I even be with Joe. I almost feel obligated to be with joe because of all the time I’ve put into the relationship… but I just don’t know about things anymore. I just have deep feelings for Carl.

Help.