Hi, Confused. I've been in your shoes...twice! Firstly, I was married for 20 years in what can only be described as a brother/sister type relationship, with a man who was a very good provider and father, but who simply lacked the romantic gene. It was completely foreign to him, and my talks to him about it just drew responses like, "I don't know what you're talking about!" So, during that marriage, I spent a LOT of my emotional energy fantasizing about other men, including real-life associations, though I never acted upon any of them to the point of sexual encounters.
One landmark experience, though, which sounds similar to yours, was at the age of 40, hearing from the man I considered my greatest love and heartbreak. After the initial phone call from him, we corresponded for months, and I lived for his letters. He spoke of love and a feeling of "urgency," after which I couldn't stand it anymore, and told my husband about our communcation and my feelings for him. I wrote to this man, my lost love, and told him that I had talked to my husband, telling him about our communication and feelings. After that...I never heard one word from him again. I didn't write to him again, but I became very ill, emotionally and mentally. My husband, by the way, was actually pretty tolerant and kind.

Not meaning to write a novel here, but here is part 2 of my similar experiences:
After my divorce, I heard from and have corresponded to this day with my high school sweetheart. He is married. I'm still single. He even visited me here a couple of times. He is in Boston; I'm in WV. I even met his wife who, after meeting me, said she would leave him with me to visit for a few hours. She is obviously very wonderful and trusting. During our two visits, it was clear that he wanted more than socially catching up. I did have feelings for him, but when he said he would be visiting the area again, I declined to see him. This pi$$ed him, and he declined to write to me for a while, but in the end, we have resolved this and are now just healthy friends. I had told him it seemed we were having an online affair (which sounds like what you are having), and that somehow this wasn't right. He responded that it was indeed that, and it was right and okay. I didn't think so.

So...I'm sorry for the long post. I rarely do this here on PC, but I thought my experiences parallel yours so much, I had to share. Please PM me anytime!
Patty