I am surprised at the responses that where given. I myself suffer, and I do mean suffer, from a similiar problem. I am not wasting my time or effort on labeling my issues, but I do not like my conduct and wish to change it. That's the heart of the matter. If you don't like who you are, you can change what you don't like. You might not get an instant cure all that will make everything ok, but you don't need to laydown and die.
I cheat on my spouse when I am away from home. Do I like doing this, well yes, but do I think that I should be doing this, no. I love my husband and want my marriage to work. I am taking steps to not want to have sex. If I know I am going into a situation that might result in a one night stand, I will orgasm before I leave the house. I am trying to keep in larger groups, with less one on one contact with those of the opposite sex. And last, but most important, I am making my sex life with my husband something to run home to. He is surprisingly more open to new and different things, and this is what I crave. A safe environment, yet still something new and wild. Meet HIM in a motel, buy toys, tie eachother up. The point is, where there's a will there's a way. If you want to keep your marriage, then fight for it.
As a side note, I do agree that you might want to seek counceling to get to the root of your problem, get checked for STD's, and then talk to you doctor about if and how much you should let you husband know. If he sees you are making a effort it might soften the blow. Take care and I wish you luck.