help!

I'm in such a hard situation right now and I don't know what to do. I'm really falling for a guy. He's pretty much everything I could think I want in a guy. And this guy likes me back a lot but I don't know why to do. Here's the issue. My best friend really likes the guy too and knew him before I did. They've hooked up but he's never liked or wanted anything with her and he's made that very clear. She thinks I should back off but I really want to see where this goes with him. What should I do? What's the right thing to do here?  (This probably sounds jumbled up but it is in my head too. But I can explain any questions)