Guys, sorry, I read a few other posts and realised I'm just too different from the majority of the people here. I do not think preserving a marriage that doesn't have passion in it is a good thing. I do not think having sex with someone is a bad thing, even if it's nor with your spouse. I do not think lust as a bad thing too, by the way, and lust certainly doesn't exclude love for me. I do respect people's responsible choice and right of privacy. Looks like 90% of the responders here hold opposite views, and often quite aggressively so.
I am very very sorry for many of you. Your life could have been much happier... Ciao!