How to pursue a relationship?

The other day my life long best friend confessed that he was gay. I wasn't surprised as he raised by a single mother, only child, & quite feminine. He's always been the one who wants to be the woman in a fantasy game, or something like that. He likes to have crew cuts & shaves his legs. He watches chick flicks with his mom, sits & cuddles on her lap & calls her mommy. His mom spoiles him & has always tried to make him like a daughter. I think he's interested in a relationship with me & i may be with him. I would be the butch & he would be the *****. But we love eachother as friends, & i think we could take the next step. We're only 16 so a ual relationship might be hard but i'd love it to happen. How do i ask him to be my boyfriend & how can i be sure if i want that?