I'm confused about my relationship with my friend? help.?

so i have this senior friend who's a guy and he has a gf and everythin and recently i've become really close to him. hes had some problems with his gf wanting him to have sex with her but he said he couldn't cuz he has a great future in football andbasketball and he can't risk gettingher pregnant and she kept trying which made him upset so we would skip half of our first block class and sit under the stairs and talk. also he recently just told m about his past where his mom beat him with beer bottles and how he has scars and he started crying and he showed me the scars and said he still crys himself to sleep sometimes. and the other day in the hallway i didn't know he was coming up next to me and i swung my arm bck and like accidentally ball tapped him and grabbed his "junk" all by accident and later that day we were talkin on facebook and he was joking around with me saying thanks for grabbing me in the hallway like that haha and i said i'm sorry i didn't try it and he said now you don't have to hide it. if you would've just asked me i would've let you. and the next day i wrote him a note asking if he was serious or joking and he said he thinks he might be serious cuz he knows he can trust me with anything and it won't get spread aroun the whole school, and he doesn't feel vulnerable around me, plus we have that whole opposite gender best friend relationship going on between us. but he has a gf so i'm confused.