First of all, I'd bet if you had the ability to know the sex life of every viable candidate that ever ran for president, you couldn't fill two hands worth of fingers with ones that weren't cheating on their wives. Its what rich, powerful people do. Not saying its right, but its true. I'm not saying it is wrong either. Why? Because I'm not John Edwards' wife or Elizabeth Edwards' husband, that's why.
And why would it be a campaign issue if he had been the nominee? Because people like most of you feel the need to make an issue out of it. If no one gave a shit what consenting adults do in their spare time then it wouldn't matter if John Edwards was doing the entire Tar Heels cheerleading squad, so long as he could campaign and govern effectively.
Oh, and while most of you are judging John Edwards, keep in mind that you don't know what the fuck is going on in his marriage. His wife is dying, you know. Its not unheard of for a terminally ill spouse to look the other way on this kind of thing. Does Elizabeth? I don't fucking know and neither do you. Unless you happen to have inside info (such as Liz on speed dial) then you have no place to judge.
Hey, try this: think of the worst thing you've ever done to a loved one in your entire life. What kind of person do you feel like now? Do you think you can criticize John Edwards? Again, remember: YOU HAVE NO IDEA WHAT IS GOING ON IN HIS MARRIAGE!
And finally, unless you've had your oldest son die suddenly, your spouse diagnosed with cancer, beat it, then have her diagnosed again with no possibility of survival, and had the entire world watch you fail at your greatest aspiration TWICE in four years, then you should probably shut the fuck up.