Seriously, what the fuck kind of man are you? You are going to call your friend who is away in the Navy to tell him you fucked his wife just because YOU can't deal with how guilty you feel. Grow a pair of balls you selfish asshole. You've already said that he knows she sleeps around when he's gone, whether he realises how often it's happening or not is irrelevant. He's chosen to stand by her, that's not for you to judge. He obviously loves her beyond your comprehension or else they wouldn't have gotten married and they wouldn't still be together. You think he wants his whole world to be ripped apart just because you couldn't keep your dick in your pants and now you feel bad about it?
You did a terrible fucking thing, no excuses, but what good is going to come of you calling him up whilst he's away to tell him about it? Just so that you feel less guilty?? He certainly won't be thanking you. There's nothing he can do whilst he's overseas. You're going to make him feel like complete shit and he may lose the one person he loves most in life...but at least your conscious will feel slightly better!!
I didn't read everything posted in this thread but Dustin seems to be the only one here who speaks any sense.
It's not your place to tell him his wife is a cheating scumbag just because you feel guilty about what you've done. Suck it up. If you have to feel guilty for the rest of your life then so be it. His wife won't be telling him anytime soon that I can guarantee. You don't know what  happens behind closed doors and is it not your place to make any sort of judgement call here. You're obviously not a true friend of his no matter what you say. And if you were able to get your dick hard you were able to make the conscious decision to fuck your 'friends' wife so don't dare use the 'I was drunk' excuse.
Telling him, when absolutely no good will come of it, just so that you can get it off your chest is almost as selfish a choice as fucking his wife was. If she chooses to tell him that's a different story. A marriage is between two people, not 3. Doesn't matter if she fucked the whole town, it's for her to tell him, not you. And how do you know that whilst he's away he isn't banging a different chick each night? You don't. Marriage is about more than sex.
If I was you, I would distance yourself from this so called 'friend' of yours, move on and chalk this up as a lesson you really shouldn't have had to experience to learn.
I'd also be prepared to live with the fact that at some point in the future (maybe a week or 10 years from now, maybe on your deathbed) you might get punched in the face.
Also, if this is a troll thread - fuck you OP!