When a man sleeps with your wife, don't blame the man, blame your wife! Men are generally suckers for a pretty face or a woman who is physically attractive and most women are in total of their actions. You set the rules down to your wife and if she doesn't clean up her act then you have the opportunity to leave. However, with that being said it is much wiser to start learning communication tools and find out why your wife is cheating on you and what your marriage problems are. No arguing or shouting; be calm. Humans are not perfect and perhaps you have been neglecting her without mean too. Marriage isn't for the weak so try working it out together.