nobody ever regrets cheating they only regret being caught .
Not sure that's true for everyone. If you're a sociopath like Armstrong I agree, but back when
everyone was cheating, some of them would be regular people with consciences (just by the law of averages). Even Floyd Landis, who avoids most people's definition of a regular human being, spoke of a weight being lifted from him once he had confessed.
David Millar does a good job of trying to convince us he regrets having cheated. I kind of believe him too. But he got caught. Who knows what he would have felt if he'd got away with it, like 90% of his colleagues in the 2000's did?
If he had continued to deny, a la Armstrong and Landis, though, he would probably have got away with it. The police had no smoking gun. If he'd stuck to his story, he would almost certainly not have lost his World Championship gold medal. That he volunteered the information that lost him this indicates genuine remorse IMHO.