How do I say sorry to him after hurting him like that?

First, I am 16 years old and in 10th grade. There's this guy that I really liked and still do. He is different than any other guy. Unfortunately, because of my mistake and people talking, he was expelled and had to do a study program near our campus. He still rides my school bus, but he isn't allowed to talk to me and he has an assigned seat at the front of the bus. My bus driver was filling out this form to give me and I crouched down a little so I could see his face in the reflection of the rear-view mirror since I hadn't seem him in forever. At the same time he turned his head and kept a steady gaze on me. There was so much meaning in it. We have always communicated with eyes. Just looking at him I could see that he'd been thinking of me knew I was suffering. It was not an "I'm sorry for you" look. If I was an emotional person I would have cried. When I got off at my stop, he kept his eyes on me as I walked down my driveway. He hasn't looked at me in a month. I really miss him and I want to say sorry. His nephew lives next door so he's riding bikes down our street sometimes and probably will be around all through summer, so I will have opportunity... But how do I say sorry? I want to be with him again. I think he's thinking of me again too. I know we aren't allowed to talk to each other but I don't care and no one will find out if we are cover. But how do I say sorry?