I will say straight off that I would never go any further than 'fancying' this man, my relationship is too important to me and I can't think of any way to describe it. 
I see this man as my son loves going where he works, we've been going there for years and have exchanged a bit of friendly banter, but recently I've began to have these feelings and I've not had them since I met my husband 8 years ago.
What can I do to stop them?
I try to rationalise it in my head and I feel awful. Like I'm betraying my husband even though I've not done anything.