That's your choice, you told him how you feel and he is not interested, you cannot force him to love you and you just let him keep using you. Don't be there for him... have you heard about let him go and if he doesn't come back it means that he wasn't yours. If despite everything you still want to be there for him then it's up to you, you just gonna get hurt more... so just end it and move on ^^
If he's not interested in forging a romantic relationship with you, then he's not interested in forging a romantic relationship with you. Of course, if he is unaware of your having a crush on him, then you really only have yourself to blame for that, Hon. Otherwise, if he is aware that you like him, but isn't reciprocating, then just accept being his friend and move on. There are PLENTY of men out there! Millions of men, actually. And by focusing on this one guy, who is apparently using you, you could very well be missing out on someone who's really great. Life is too short. I learned that the hard way many moons ago.
The friend zone is bull. It's really just whiny babies complaining because someone has the audacity to not want to date them. Did you tell this guy how you feel? If not, chances are he doesn't realize you feel that way. I was friends with a guy for years. We were really good friends, hung out all the time. Eventually he revealed he'd had a crush on me the whole time. I'd never noticed. Fortunately, he was mature enough to accept that I only saw him as a friend.