I like my best friend's crush, help?

Okay, well, my best friend has been liking this guy for a while now, when she introduced me to him, I was like okay, what ever, but when I started to get to know him and stuff I developed a bit of a crush. Then it's been like a month or so and I've been liking him more and more, but I haven't told anyone. Then I went to camp and he was there and on the bus, one of my friends told me that he liked me by the way he was acting towards me and I got to know him a lot and there was drama because my best friend told this girl she liked him, but the girl was like flirting with him a lot, a lot. And she started liking him, on her Myspace she wrote things like "With him<33" and other stuff. And my best friend hates her guts and called her a "dirty asian skank." Now, today, I went bowling with my church and it was just me, him, this other girl, his big brother and a few little kids. We were like playing around and stuff and bowling and he asked me if I wanted to go to the movies, I said yeah. [[He asked like everyone there, so I guess I didn't really betray my best friend]]. Now, I'm like way deep and I can't tell my best friend and I really like him. I have no clue at all at what I should do, please help!