Someone give me advice before he leaves!! please!!?

okay so im in love with this guy. i realize it this year after three years of knowing him. lets call the guy i love blue. so me and blue first met two years ago in a class we had together. we instantly clicked. we became friends right away. later on we started to become close and close. we would always make each other smile,laugh,and we never had a bad time like we never argued and ****. so then about 3 or 2 months before school was going to end, our teacher switches everyones seat including ours. he sat in one side of the room while i sat on the other side. we were far away from each other. we couldnt talk. i would just try and make him jealous. we still did talk but when we lined up in front of the door. the next day of the teacher had switched our seats. everyone went back to their own seat because they didnt want to move. he said oh wait, this is forever? and looked at me and smiled and i smiled back.we did still talk. over the summer we didnt talk at all. we came back from summer break and we didnt say hi or anything. we just looked at each other most of the time but never spoke. i did get over him but i would always get feelings back whenever i saw him and i would get nervous to mess up around him. we still did look at each other. then summer came again and we went back again. i liked another guy until december i liked blue again. my friends told me to talk to him so i did. at school it seemed really awkward. we didnt talk just looked at each other. i still liked him but we started playing this" game" where we would look at each other, he would walk really close to me, brush his body against mine and etc. we did that until the end of march. in february the day after valentines day he seemed really depressed. he wouldnt do anything just sit and look at me. my friend told me he was looking at me the whole time with a deep thought expression. he also sighed sadly layed on the floor said hi to her and sat back up. he also was still looking at me and sighed sadly again and ran his fingers thru his hair frustrated. i was worried and wanted to ask whats wrong but i didnt. we kept doing that "game" until the end of march. i started getting over him because i was tired of waiting for him to come around and talk to me. a girl i knew came to me and asked how was he because i told her i liked blue. i told her oh i got over him and i told her who i liked. one of his friends was in front of me and her and he was hearing our conversation. the day after that i stopped paying attention to blue. i started paying attention again in the middle of may. i saw he had changed a lot! before he was a quiet good boy. now hes an attention seeker and laughs at the littlest things from his friends. before he used to be with his friends from his country. now hes friends with people who are popular. he changed in a matter of weeks. lots of my friends said it was because he noticed i stopped paying attention and wanted my attention again and did that. im not sure about that but anyways i tried to talk to him again last month but he never answered the message i sent on fb. the next day he was looking at me a lot and started acting like himself again being quiet and was talking to his old friends again. he did this for a week. the next week he acted as the douchebag again which got me upset. i tried to ignore it but i couldnt. he would also still look at me even though he acted like a douchebag. he kept doing the same and tried to bump into me but never succeeded. on the day of the dance he was watching me dance with my friends. i would also get upset because he was dancing with other girls or grinding with them but he would look at me for like two minutes. when i would be dancing with my friends and him sitting he would look at me longer. on the day of graduation he was looking at me too. on the last day of school he seemed quiet. in a class together he had his head down and was looking in my direction. he wasnt loud. or laughing at small things. he was just talking for a few minutes then put his head down looking in my direction. in another one, i was upset because of him he was staring in my direction when he was talking to his friend. i was hearing music and i looked upset. even when he was in a group his body was always in my direction and i guess he would glance at me a few times. after class he was usually loud and yelling. after class he was walking slow and was quiet and was looking behind him. that is the whole story between me and him. what should i do? did he ever get over me? also hes moving next week to another country. i am friends with him on facebook. also i cant tell him face to face because school is over and i dont see him anymore.