the guy i like told my best friend that hes known that i liked him for awhile how do i respond!

Well if he knows now then there is a sense of tension, I would recommend that you just put it straight out there in the open so it is no longer a burden. Then once you have done that it makes it officially his choice and if he says no, then try to move on. If yes then have a lovely relationship. When telling him make sure that you tell him that if he does not want that sort of relationship then you are happy being friends. This means that the potential future awkwardness isn't possible. Good luck!

Well if you know he likes you whats the problem? If I liked someone and I knew they liked me I ask to talk to them and tell them how it is and how I really felt about the person. If he told someone else he likes you I don't think you have to worry about rejection. If it is he may just not be ready, just give it time and talk to him. Hope all goes well :)