The rat congressman was the ranking member of the committee meeting in closed session. He described the Republican congressmen present as incredulous at the explanation given what the Pentagon had already told the Senate and hostile to Petraeus. He made his remarks on September 14th. In the intervening two months no Republican present at the meeting has contradicted his characterization. It's pretty safe to assume the story is true. What are the rules about divulging testimony in a closed session?
And as I've pointed out in another post, an unnamed source supposedly has contradicted what the Democrat congressman said.
Nothing divulged was classified, so it's unlikely there is any Congressional rule governing it.
As for the rebuttal; sorry, but I place a great deal more faith in a NAMED SOURCE -- even if a 'Rat, when the GOP has had two months to call him a liar and hasn't done so -- than I do an unnamed source, who can say anything without fear of contradiction or reprisal.