It's an interesting question, HoneyDragon. I'm not a lawyer, so can't give you a definitive legal answer. I can't see, however, how a libel "victim" could be held liable for repeating an allegation about themselves: who would sue? They'd have to sue themselves.
But even if someone publicly discusses an allegation made against them, I am not sure that would let anyone else off the hook if they were to repeat the allegation on the web. The aim if defamation law is to stop unfounded rumours from spreading, hence the tort of repeat libel.
I just wanted to raise the subject, because a lot of people are unaware that if they post something on the internet, they will be bound by the same law as someone writing in a newspaper or saying something in a TV/ radio broadcast.