Writing a letter?

last year in 11 grade, there was this boy in my cl who seemed interested in me, would never stop looking at me, etc. To tell you the truth, he changed my life.The first one to ever like me. Im a girl who has cerebral palsy and has difficulty getting a guy to like. This guy basically changed my life. However he had a girlfriend though, and right know in 12th grade he still does. Sometimes when he is not around his girlfriend he still looks at me other times he doesn't. Basically in other words last year, he was the only one who could look deep into my eyes and see the beauty inside me, doing his best trying not to burn it out. Right now, i still have feelings for him. I am not trying to persuade him to become my gf, i am trying to tell him my feeling about how he has changed my life and all. I want to say all of it in a letter, so it can be a bit private and all, will it be too much or will it be the best way to tell him my feelings? i am not trying to take hiM away from him gf.