Yes. We are cheaters. Get over it, it's normal.
My definition of cheating is this: If your SO would disapprove of it if she knew about it, it's cheating.
It is NOT your wife's fault that you cheat. If your relationship with her broke down and you aren't having as much sex as you like that's not only her fault. It's yours too, maybe for reasons you're unaware of. Anyway, I don't believe there is "right and wrong" in a relationship: There's a complex interaction between two people, where cause and effect becomes blurred and murky in one of the deepest, most intimate, and most difficult to fathom of human experiences.
That said, cheating is a natural human condition. It's in our genes, part of who we are, and you repudiate something fundamental about your own being if you suppress your urge to cheat.
Everyone here loves me for saying this, so I am going to say it again:
Have enough class to cheat discretely, so as to protect the feelings of your loved ones. If you get caught you're an asshole, and the probable reason why you got caught is you did something crass like bring your date to the home you share with your wife, or you came home smelling like perfume, or you used the computer you share with your wife to view escort ads or email your girlfriends. Show her some fucking respect, keep your cheating discrete.