Wow, this sounds like I would have wrote 6 years ago. The only advice I can give is from my own personal experience. When I was your age, I was madly in love with my best friend. He was 25 at the time, and I was a virgin. I had the same fears that it would ruin a friendship, and that I would lose my best friend. (I'm guessing he is your go to person, who you feel the most free talking to, and stuff)
My advice to you is tell him how deep your feelings go. If he is truly a friend, he won't abandon you. Telling him will make you feel like a weight has been lifted off of your shoulders, because you will know longer have to worry about him finding out.
I told my best friend the depth of my feelings for him. He stated he was flattered, but did not feel the same way. We kept being friends, and my feelings went away eventually. Until one day, 2 years later, him and I were at a bar (no, we were not intoxicated) and he leaned over and started talking about the night I told him I had feelings for him. He told me that he wished he could go back to that night, and tell me how he really felt, how he still felt. My feelings all came rushing back, and we started seeing if we could turn our friendship into a relationship. My best friend is now my husband.
I wish you all the best, and I hope you, (and your friend when you tell him) find peace in your friendship, and figure it all out.