How do tell my best friend I'm in love with him?

so my best guy friend and i have liked each other for about a little less then 2 years. hes would say cute and romantic things about me almost every day he even gave me a nickname Kat. we really liked each other he even asked me out but i wasn't ready then. he'd also tell me how much he missed me and wanted me home.(I'm at college in another state 1:15mins away from him) one night we were chatting online and i told him i messed him and he told me ';well i hope you'd miss me as a friend'; and i then told him ';no as more then a friend'; we then spent the whole night arguing and he told me he didn't like me that way and we could only be friends bc he could handle and long distance relationship. I got upset bc my feelings for him were and still are strong. I love him and i fall in love with more each day. my friends think that i should just forget him but i cant I've tried.I don't want to lose him. i have to more years left of college and he told me he cant wait that long 4 me. I just recently found out he has a date with a girl in 2 weeks. it hurts that i love him and he doesn't know. I don't know how to tell him. and if i do tell him I'm afraid I'll lose him as a friend. I can't bear to lose him. Any advice would be great. I don't know what to do. I miss him so much!How do tell my best friend I'm in love with him?
write him a letter, if yall stayed up fussing about ur feelings online how can he fuss with u through a letter? don't let him go..