Apologizing to Crush?

I had a crush on a guy who was a year younger than me, but when my friend asked him if he liked me he said no. He did some mean things, like completely ignore my friend when she asked him to come tell me himself. He also just yelled that he didn't like me in fromt of everyone. I was really mad, so at the end of the day, when we were coming out of school, I wrote him a note, and asked my friend to give it to him. It said that I didn't like him anymore, and I didn't see how any girl ever could. I also said I hated him. The next day I felt so guilty. I don't think he really meant to hurt me. I am going to apologize to him tomorrow, since it is the first day back from march break. How should I do that? Oh, and I'm 13 and he's 12. Any tips are greatly appreciated.