I'm 16, gay, and attracted to my friend. I don't know if he is gay. He's shown some signs, but idk what to do.?

Ok so I have a friend that i think is possibly gay. I've never seen him talk to any girls, look at any girls, or even mention anything. I've known him since 9th grade (we went to different Middle Schools), and we are both going into senior year after summer. He sometimes jokes about sexual things with me, or he'll put his hand on my knee (every morning me and a group of friends sit in the hallway of the school waiting for first period to start) and keep it there for a good 30 seconds, and he also once mouthed "i love you" to me, and i really can't tell if he is completely joking or trying to hint to me that he's gay...I'm gay myself, and absolutely no one knows (not even my parents/sister whom i'm very close with) that i'm gay, and i'm attracted to him. idk what to do. i want to tell him i'm gay and see if he tells me he is also gay, but i'm afraid that maybe he's not, and i don't want our friendship to fall apart because of this. We're not the type of friends that really hang out after school, but im considering asking him if i could come over his house sometime so i could tell him. any advice on this subject?