Retired US Army Col Steve Boylan, an ex-spokesman for former CIA director David Petraeus, has told ABC News that Gen Petraeus' wife, Holly, is outraged by the revelation of her husband's extra-marital affair.

"She's not exactly pleased right now," Col Boylan said. "In a conversation with David Petraeus this weekend he said that furious would be an understatement."

Col Boylan also told ABC News that the four-star general's affair began months after he retired from the army and ended about four months ago.

Gen Petraeus knows that he made a "colossal mistake", Col Boylan added, and is focused on repairing the damage with his family.

Gen Petraeus unexpectedly resigned as director of the CIA on Friday.