In love witth my straight friend?

I am 15 and recently come out as being biual to my close friends. Before I came out, one of my friends used to make jokey moves on me. He once tried to sit on me frontal ways before perching himself on the sme chair as me outside the german exam when no one was there. Then he put my arm round him and putt his hand on my knee. Other times, he would sit with his head on my shoulder on a bus and recently he stopped, after he stopped i came out to him. He was fine with it and, if anything it made u better friends. I have, however got strong feelings for him, genuine. He has pics of girls on his wall nd says he is straight but i am unsure. I have written a letter that i may give t him telling him how i feeel. Any advice on what to do?