Gone but not forgotten?

I've been pretty "goody-goody" most of my life with the exception of one event that happened in 1998. And the same thing is happening now. In 98, I was a single parent, going through a divorce and was captivated by the "guy next door." I had never talked to him--just thought he was the most beautiful man I had ever seen. One year after living by him we "spoke." Within 2 weeks he left his girlfriend (who he had been living with for well over a year) to be with me. But he wanted to move in with me. I wanted him to stay with his parents while he and I transitioned slowly. After an ugly month (including threats by the jilted female next door) he and I separated and he went back to his girlfriend. They moved. Down the road. I was crazy about him. So crazy that when he called me and asked me to meet him in secret, I agreed. After 2 months I got some pride and decency and told him NO MORE. Throughout the years, I have never been able to forget him. If I see him my heart races. I moved away 4 years ago and remarried. But 3 months ago I signed onto yahoo and there was an add request. It was him. The man I had always referred to as "the one that got away." He told me that he had never stopped loving me. (He is with someone else now, by the way.) He wanted to see me. I somewhat agreed to meet him. Then one day I come walking into my bedroom as my crying husband comes walking out. I had left my yahoo open...and he had checked out my archives. I told him that I was sorry and that I knew I had betrayed him. He emailed the old flame and told him to stay away from me. And the old flame did just that...until yesterday. Yesterday he messaged me wanting to see me again. I am so screwed up. I love my husband...I know this. He doesn't deserve to be treated like this by anyone..most of all ME after all he has done for me...yet I am considering meeting the old flame...just once. For conversation. He is SO intelligent. And of course. Why am I so captivated by this man? Why can't I let go?