GUY HELP !!!!!!!!URGENT?

ok so I went out with this guy matt (boyfriend) a couple of yrs ago and now hes goin out wif my other friends. PS: i went out with hime 2 yrs ago so its alrite. I just found that i like him. He always talks to me and stuff and i have a lot of guy friends at skool and they say hes always talkin bout me and everything. I cant tell him because hes got a gf already. I went to the shops with a group of friends and some of his friends and they said i looked really hot and everything. It was holidays and i went on a diet and all my pimples went away (i didn't have many) and i got my braces off. school starts tomorrow how do i make a big impression and yes I have to make a big impression anyway because im popular at school and everything. PS:i hope i dont sound full of myself i dont mean to sorry if i do.