madly in love with married coworker

I'v been married for 14 years, love my wife and never dream of cheating on her. I work with three coworkers, 2 men and a (married) woman, we have known each other for more then ten years now, and always got along very well. We (She and I ) have a lot of things in common, like music tastes, political ideas, and so on, so we talk now and then, even though lately she only talks about her children, wich i find a bit boring. Our work is mostly office work, but once or twice a week we have to go out on the territory to take samples and make measurements, and we always go out in pair, most of the times I go out with my male colleagues, but recently it happened that I went out 2 o 3 times in a row with her.
Some days ago iI was eating in the cafeteria with my colleagues (she was not there) and another guy , who is known to get very provoking and annoiyng at times, commented on my going out with her by sayng: well, we all know that you are lovers” the others at the table made a half laugh and i laughed too, saying “oh please, stop it” because the idea of us being lovers seemed absurd and bizarre.
But later i came to think about it, and the idea of us being lovers came to my mind us something extremely exciting in its impossibility, I considered her in a completely new light, now she become suddenly very attractive to my eyes (which she had never been, actually I never thought that she had been pretty).
Now I can't literally stop thinking about her, I find every excuse to talk to her or to be where she is.
I know that this thing has no hope to become a reality, she is a very faithful wife and responsible mother (or at least she tries to look like one) on the other hand I woul never dream to tell her my feeling or to put my marriage in danger. I wonder why it happened and how it could happen,, and since I won't ever tell anyone, I nedd to tell someone anonymous just to have some feedback. Thanks