Im sooo lost and i need major help?

Ok there's this Boi Mike Veno.. he's a senior football player... he's mostly like my big brother we've known each other since i was born... i used to go over his house all the time when we were little kids well that stopped after a while until we met in highschool again and about a year and a half ago i started having feelings for this boi i call my "big Bro"... well now i like him even more than i did before...he flirts with me all the time and even danced with me at our halloween dance... we slow danced and he was grinding up all over me... well it so happens he has a girlfriend i'd do anything in the world to be with this boy but i dont wanna rip him and his girlfriend apart. But i know he has feelings for me and i know him and his gf are gonna be breaking up... How do i really find out if he likes me... Why am i starting to have these feelings about this boi i call my Big Bro???