I think you should try going out with him again, it's not your fault that your best friend also likes him. If he likes you then go back out with him. Things will work out in the end with your friend. That is the best advice I can give. Good luck.

I had a situation like this. actually me and my best friend liked the same guy, but the guy liked my friend, i understyood that u know it was nothing and if they love each other they should go out together, so i told my friend to go out with him, because if she doesnt he's not gonna like me, they both just will be sad, so i think your friend should understand that too, but even if she doesnt, u should go out with hima, bcaz its not your fault that he doesnt like your friend. or maybe u should talk to ur friend first.