I, too, am a married woman having an affair. And I feel the worst about lying where I am. My husband and I have been living very separate lives for a long time, so it's not hard at all to make things up, and he isn't suspicious. I get together with "friends," I go "to the mall," even to a movie by myself, or stay later at work.
The way I justify it is that he has lied to me for so many years about his lack of sexual desire. He has never had a straightforward conversation with me about it (not for my lack of trying), nor has he really tried to do anything about it, like see a doctor. I consider this cheating. I know it sounds terrible, but this helps me justify my lies.
I don't feel guilty about making love with another man, however, not one bit. It's beautiful, passionate, and a lot of fun. We have a physical and emotional connection on a deep level. He is a lover from my past, 25 years ago, who reappeared in my life at the exact moment we needed each other.
I am not planning to divorce since we have a young son. In a strange way, I have incorporated this affair into my family life. I am happier and feel more alive than I have in many years. I wish I could just tell my husband about it and have him feel relieved or something. Does anyone else feel that way? Maybe they could just say, "Great, I'm happy for you!" Given that he isn't interested in the goods, why should he mind if someone else is? Wishful thinking, I guess!