Two. One that I felt bad about, one that I didn't. Neither while I was married (although if your own wife counts you could add two more, one for my first wife and one for my current wife).
The one I felt bad about
: Met her playing an online video game. (Had sex with two women that way, the other one wasn't married). Played long term, chats got racy, we lived close to each other. Soon we were seeing each other and having lots of great sex. She had kind of an average face but an incredible body and it was a great time. But...then I found out she was married about two months in to our 'relationship'. How did I not know for that long, you may ask? Because the husband was DEPLOYED TO AFGHANISTAN. Yeah....so, that ended rather abruptly. I have too much respect for guys willing to put their life on the line for my sorry ass to be banging their wife behind their back while they are getting shot at.
The one I didn't feel bad about
: I wrote a big story about it on the boards here. SUPER hot petite Cuban girl that I had known for years that apparently had a thing for me the same way I had a thing for her. She was on her second husband by the time I started sleeping with her, but he wasn't worth a damn and her first husband had turned out to be a jerk too, so I had zero regrets
