Congressman Foley resigned, as he should. Dr. Sanity discusses shame and guilt cultures in a post from last year, and I think the distinction between guilt and shame might apply here. Resigning from Congress could spring from either guilt or shame (or some of both), but I think other information suggests guilt.
My own personal soapbox on this is self-respect versus self-esteem. If our goal is self-esteem, then when we do evil things we are hopelessly lost. After having been caught making wildly inappropriate sexual comments to a 16 y/o, reliance on self-esteem would leave one forever wounded. But if your goal is self-respect you can at least make your next act honorable. If you have nothing else, you can at least reassert your ability to make some moral decisions correctly. It is in some ways more painful, because your ability to make a correct moral choice on Tuesday implies pretty strongly that you had that capability on Monday as well. But it is at least reality. You can salvage something. With self-esteem, you either have to accept that you have none, or start lying to yourself to get some.
Tangentially, I am always grateful for sins I'm not tempted to. I don't do so great with the ones I am tempted to, and I'd hate for that list to be longer. So I am hesitant to condemn in detail people who have done things I never could. I'm harder on those whose temptations I understand.