Usually liars go through a routine when caught. First they say, 'you got it wrong. I didn't say that.' Then, when that doesn't work, they say, 'uh, I misspoke. I made a mistake.' And if that fails, then, 'Gee, can't you take a joke? I was just kidding.' (At some point I expect Kerry to explain how his Cambodian adventure, plus his entire Vietnam experience was just a joke. As a matter of fact, his candidacy is a joke. His political career is a joke. TerAYsa thinks he's a laugh riot.( Not.) I guess she doesn't care for public humiliation.
He's built up this whole charade about him being some sort of heroic patriot/victim that he's starting to believe his own lies. The fact that they weren't well-conceived when he first made them has been forgotten by Kerry.
He successfully used those lies to build his image in the past, and it has to come as quite a shock that they are actually being scrutinized for the first time.