Okay, Mr. DGA, first, you need to pitch in around the house and help her out. But don't think of it as a quid pro quo...just do it because it's your house/food/clothing, too. This ain't "Leave it to Beaver." Second: DGA, are you on any drugs that may affect your sex drive, such as Prozac? If so, you might want to ask your doc about alternatives which may not have a deleterious effect.
Third: Mr. DGA looking at a website about anonymous sex partners. While this is not the same as actually catching him in the act of hooking up, what did you expect? He didn't marry you because he wanted a roommate or a maid. He wanted a wife, and most people think of a marriage as a partnership with the added ingredient of physical intimacy. If you didn't want it, you should have been very clear about it up front. You can't just change your mind midstream and expect him to accept it joyously.
It may not be right for him to be trolling for babes, but it's not unexpected. Consider it a warning buzzer.
And I'm not defending him, either. Mr. DGA, if you're going to screw around, have the balls to divorce her first, before you screw up everyone's lives.
Other questions: do you have kids? And just how often do the two of you ML now?