Do I really love him? Or Is it something else?

Okay so I have a guy best friend of 8 years…he knows me better than anyone and he’s like totally in love with me. I even told him that it’s not right because I only see him as a best friend..like a brother but he says that he doesn’t care because that doesn’t change his feelings. Anyway, I told him yesterday that I have someone I like and he started saying that he’s only being a burden on me and the guy I like..and that he should just disappear from my life and stuff like that. He said that his love is holding me down because honestly..whenever I start liking someone, I start feeling guilty and as if I’m “cheating” on my best friend…but I never get that romantic feeling when I’m with my best friend. When he told me that he’s going to disappear and stop being my best friend, I kind of snapped. I didn’t want that to happen because he is my best friend of 8 YEARS and it’s like I’m loosing half of myself. I told him that and he says that he thinks I may be in love with him..and that confused me even more. I love him but is it romantic or like a “sibling” love? I need serious help because I don’t want him to leave and never talk to me..but I hate that I always end up hurting him whenever I start liking someone…What should I do? Or what should I tell him?