What should i do?

So there is this guy that I work with and I have a crush on him!! I didn't start liking him till everyone around us said that we were flirting. So I asked one of his closest friends about it. She laughed it off and said he doesn't like me and that he is just awkward. So I stopped flirting but now he flirts when we are alone together, but when we are with all of our coworkers he can he a real jerk sometimes!! I'm afraid to talk with him about it because I don't want to loose a great friend but I can't stop thinking about the possibility of us being together!! Help!!