Can being infatuated with someone cause depression?

About 3 months ago l fell for a guy who works for me. He has totally blown me away and l spend every day thinking about him and feel like l have lost the plot as nothing else seems important anymore. l was told he really likes me but doesn't want to spoil the working relationship. l have tried to talk to him but he makes me so nervous l just clam up. He always seems to be trying to avoid me and now i just feel stupid. His brother told my friend that he needs someone who isn't so shy and that takes control - l'm not like this even though l want to be. Every day l feel so depressed - l really want this feeling to go and to be able to get on with my life as l seem to be breaking my own heart. l don't know what to do.