What do you do, When you're bordering obsession, But it's nothing but impossible?

There's a girl, Who honestly I couldn't flaw. It's Clich� and over written but she is just everything?. I'd say one in a million but that would imply there are 7000 people like her, I'm only 15, So by saying the word I'm about to say instantly deems me as "Shortsighted" Or "Pathetic" But when I'm with her, Or when I think about her, There is honestly nothing else I want in the world. She's just everything to me, I'm just a normal guy. With a sub par appearance. But some how, We are best friends (And she Is the one organising things). I was a self conscious, Pessimistic, Buzz kill before I met her, But now I literately just feel so happy nearly ever day. And I spend hours thinking (How come I get to know her, How does this even work. Or when I slept over for new years I found myself thinking "Wait.. I'm in a girls house right now (Never done everything like it before). I can't verbally express how amazing she is, To do so I would have to sing her "Bruno Mars - Amazing" Several million times. It's like she is flawless. I'm not love blind, But people have such a wrong idea of her, due to a horrible rumour, I digress. I can't get her out of my head. Today I went to town. With a friend and the entire time I didn't reply to him. I was to busy just thinking about her, Not ually (Wouldn't even want if it ruined a friendship, Stopped her drinking and carried her upstairs when she offered it (As well as help her be sick. But again I digress) (Very Very drunk) So what can I do. If I ask her. Then Bang it's out there, But if she said no. I'd want to do for die for ruining it. And plus are friend group (Of 4) Would be ruined and I can't ruin our friend group it's just not fair. And even if, somehow. some way she said yes. There's a tension between our friend group (In our friends group the two girls and best friends and me and the boy are). And we couldn't meet as often. How ever I'm fairly certain she doesn't as she is liked by a 19 year old (She's 15). And while at said new years party she said in the next year she wanted to at least kiss him. So I'm in this situation, What do I do, I'm spending my life wallowing in unrealistc bliss. And it isn't going to stop? I can't tell her. But I always see her. This problem's so bad It's made me look up somewhere to ask this question and then made a account, I'm that desperate. Please what do I do.