Just tell him how you feel. Only one of three things will happen; he will feel the same way and you both will be happy; he will just want to remain friends, or he will freak out and not want to stay friends. I've been in that situation and it worked out perfectly for me. I wish you the best of luck!!
i have the same problem, you can look up best friend love and find my confession about how i am in love with Christian but i can't tell him, or I don't know how to tell him