Do I have to tell a boy I like him?

Last year I had to work on a project with one boy. As it was a long-term project, we had to work on it for weeks. At first, everything was fine, but then I realized that I like him. So I decided to tell him about my feelins, but I said it with an ironical voice, so he replied "Yeah, nice joke" Since then we became good friends, I have helped him millions of times, and I have defeated him many times. I have fallen in love many times, but around him, I feel differently. The problem is that many times I have not followed my dreams, and am sorry for my desicitions now. I really like this boy, but he spends lots of the time with girls, so I would assume that he is straight. Does this mean that if I tell him about my feelings, he might put an end to our friendship, or would he take into account the many times I have helped him, or what?