In Love With My Best Friend =/

I really like my best friend. He just moved to Maryland from Florida about a year ago. He is 17 and a junior and I'm getting ready to turn 16 and a sophomore. We met in school and we immediately became close. He told me he had a girlfriend back in Florida and said he loves her, and wants to marry her. But just recently he was telling me he is suffering from depression and is having thoughts of breaking up with his girlfriend because he doesn't feel the same way about her. He told me he talked to her about the depression but she won't listen to him and tells him she doesn't want to talk about it because "he is just going through a phase. On the plus side, he is always playing around with me and finding reasons to touch me and wrap his arms around me. He even asked me to spend the night with him one Saturday night. But he doesn't do this with any other girl. I feel like I'm getting mixed signals and I have no clue what to do. He told me he is moving back home when he either turns 18 or when he graduates. I don't want him to move back while wondering what could have been between us romantically. What I need help with is should I tell him I like him, and risk losing the friendship, I can take the rejecting but I don't know if I can take losing him completely as a friend too, or should I not tell him and wait it out to see if he makes a first move. If I should tell him, how can I go about it without making it awkward or bad for the friendship? If anyone has any advice, please help me! I'm hopelessly confused and will greatly appreciate it. Please and thank you! =D