Don't deny that you obviously have more than friendly feelings for this guy. No matter how much you protest, it's pretty obvious.

Don't be so selfish.....he has a wife. Whatever feelings you have for him, keep them to yourself, it will do no one any good to put them out in the open. Go get your feelings out in a diary or with a close friend. I know you say you don't want to ruin his marriage, but you have to ask yourself, be real: What is it you're REALLY hoping to gain from imparting this knowledge to him?

My guess is, its not 'friendship'.