What does he think of me? 10 points?!?

Alright I will try and not make this too long. I have known a guy for almost a year now and we talk close to every day. Hes really really sweet but has a low self esteem. He always tells me how much he loves talking and how Im an amazing friend and that he couldnt have gotten through everything without me...he even wrote me a letter telling me all the things that are amazing about me. He asked me out more then once but I can't date him because my parents won't let me. I really like him though! Later he won a competition and a girl that was really mean to him and fairly mean to me asked him out and they started dating. Now I still talk to him a lot and he still tells me Im an amazing friend ect. he just gave me the letter last week so nothing has really changed between us. Also in the letter he told me Im the prettiest girl hes ever known and his bestest (yes bestest) friend ever and that I can always make him happy. We have so much in common and I really like him but I can't tell him because hes dating a girl and who would that help? I cant date him anyways! It's still really hard for me to see him in that relationship though. What should I do about all this? Thank you soo much for any answers!!