Hopeless. In love?? Advice?? What do you think?

It was a happy day, I arrived at school and I was just staring out into space for a couple seconds ,then I turn my head to the right , and a guy I had never seen before was staring at me with such idk it was like the world stopped for a minute and it was just me and him and a diagnal path between us. I felt wonder and infautiation rushing through my body rapidly. I don't know for how long he had been staring at me but I felt like he appreciated me like he knew me or even loved me by thewayhe stared. He smiled and the bell rang. I had to go and he almost chased after me. It was the most unexpected thing ever. I thought I had given up on love completely because of a past dissapointment andpg then he came along. It was wierd. Our homerooms were right next to eachother the next year. He hadn't talked yet but the paths we took were almost the same. Sadly he did say hello but I was in a hurry and didn't say hi back. He even got to know my friends to get closer to me. I never put much effort. But I did feel things. He always stared with tenderness and smiled and I felt like he payed attention. One day it was raining and he was inside and I was outside. He looked at me outside and once again I felt like it was just the two of us.the year went by. And it sucks because I still like him. He's going out with my best friend. When I found out I cried. She didn't know about the eye affair I guess you could say. Why though? He got close to my friends and now he's going out especifically with my best friend?? Advice??