I had an affair with a married man, off and on, for a few years. It started for similar reasons, I was alone and craving physical touch, he was unhappy in his marriage but wouldn't leave because of his daughter. I know I started developing feelings for him early on, but he noticed quickly and put a stop to things. For a while. After a few months he started contacting me again, and I was sucked back. This time I knew to keep my feelings hidden so he wouldn't leave again. It was horrible for me. I felt so un-cared about and used, because it was only about the sex. I even gave in once and used him to cheat on another guy I was in a real relationship with, which ended that.

After I broke things off with him, I thought I would never find someone again. But it wasn't long after that I met my current boyfriend, and he's the best thing that's ever happened to me. I don't remember if you mentioned how long you've been single for, and I know it's hard to do, but being in a "real" relationship is so much more fulfilling. Your partner is devoted to you, and you alone, rather than just using you for escape or for better sex than she is getting with her husband.