What should I do now?

My buddy and I were best friends since we were 4. He's really humorous, he always makes me laugh and I have a peace of mind whenever we spend time together. He also has lots of thoughts and opinions that are different from others' and I think he's so interesting. When we were in 6th grade, I thought I liked him, but I didn't tell him because I thought it was just a temporary feeling and I was afraid we wouldn't be friends like before anymore if he didn't understand me; I also thought that feeling will disappear soon. However, 3 years later, my feeling about him just doesn't change and I think I'm falling for him, but I still don't want to tell him since I don't want to lose our friendship, which has lasted for 10 years. Yesterday, my friend told me that LOTS of girls in his class like him; well, most of them like him because of his appearance, when he is quite handsome, in my opinion. Now, I don't want to lose him, but I don't want to lose our friendship, either. I just want to tell him how I feel about him since he meets the girls in his class more often than me (we don't study at the same school), so they have more opportunities; but at the same time, I understand that he is a freedom lover, and I'm still afraid that we won't treat each other as naturally as before anymore if he doesn't like me. So what should I do now? What should I do to show him how I feel about him? Please help! I don't wanna lose him! :(