it sounds like you have a crush and from that have inferred all types of things.
are you friends with him? why not trying to be friends and see how things go from there. you might find he is not the person you imagined, or that he is not in a relationship with your co-worker or that he doesn't have feelings for you. you're running yourself ragged with lots of assumptions and it is before you've even had a chance to get to know him. one step at a time.