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 it is just us together,but when we are with all of our other coworkers he can be a real jerk some times!!! I'm afraid to talk to him about it because he is a great friend but I can't stop thinking about him!!!