I need really good advice...?

I am married with two children but in my opinion the marriage isn't doing too well. Anyway...the bad thing is I have developed a huge crush on my coworker, who is also married w/two children. I have had a crush on him for a little over a year or so. I am NOT a home wrecker. I would never do or say anything to him to start an affair because I am way to shy. I have said to myself that this is a silly crush and that I will get over it with time. From time to time I think I have gotten over it then he will come to work looking really good and my attraction to him starts all over again. This is the worst part...I have tried everything to forget about him because I know nothing will happen but I can't. He keeps popping up in my DREAMS! dreams! I am not thinking about him before I go to sleep because once I get home I am way too busy with my kids. But as soon as I think I am over him, weeks will go by and I have a dream about him and I am infatuated with him all over again. How do I stop this crush? How do I stop dreaming about someone I can't have?