What to do in a lesbian love triangle?

Maybe not love but deep infatuation. The thing is this, I've always though one of my friends was beautiful, and the other day I was contemplating asking her out, on a date, more than friends. She confessed to me before I asked that she likes this other girl. Now here's where it gets weird, the other girl likes me and she had asked me out before, but my friend doesn't know that. I'm totally confused as where to go from here.