I have been badly infatuated by my colleage at work- please help?

I fell in love with this guy who wants to be only my friend. I see him everyday at work, he doesn't want anything else more than friendship but flirted with me and showed signs of jealousy whenever I talked to other guys. I felt like he was controlling me, and started to ignoring him for the last 2 weeks. I know it sounds childish but it just makes me feel better when I don't see his face. Any advice? Did anyone have similar problem? How can I end it? I am very much in love with him and hurts me when I heard he went to see his ex-girlfriend.