The career of David Petraeus, the CIA director and renowned general, was derailed by allegedly vicious emails his paramour sent to another woman. Now the CIA, FBI and White House face questions from Congress about Petraeus' love life and how his emails came under investigation.

And he may not be done with Capitol Hill himself.

Petraeus quit his post Friday after acknowledging an extramarital relationship.

"It was like a lightning bolt," said Sen. Dianne Feinstein, who leads the Senate intelligence Committee and planned to have Petraeus testify this week on the Sept. 11 attack that killed the U.S. ambassador in Libya and three other Americans.

Feinstein, D-Calif., said she first learned of Petraeus' affair from the media late last week and was dumbstruck when Petraeus confirmed the affair to her in a telephone call Friday. She said she has since been briefed by the FBI but wants to know why the bureau didn't notify her sooner that the CIA chief was at the center of a serious inquiry.

"We are very much able to keep things in a classified setting," she told "Fox News Sunday." ''At least if you know, you can begin to think and then to plan. And, of course, we have not had that opportunity."

Petraeus had been scheduled to appear before the intelligence committees on Thursday to testify on what the CIA knew and what it told the White House before, during and after the attack in Benghazi.

It now falls to the CIA's deputy director, Michael Morell, to answer lawmakers' questions about the attack on the U.S. Consulate and CIA base.

Feinstein said she hasn't ruled out compelling Petraeus to testify about Benghazi at a later date. "We may well ask" him at some point, she said. "I think that's up to the committee."

Meanwhile, Morell and the FBI's deputy director, Sean Joyce, also will be asked for answers about who they informed and when in the Petraeus investigation, in meetings with congressional intelligence committee leaders this Wednesday, according to a senior intelligence committee aide.

The director of national intelligence, James Clapper, was told by the Justice Department of the Petraeus investigation on election night, and then called Petraeus and urged him to resign, according to a senior U.S. intelligence official who spoke on condition of anonymity because he was not authorized to discuss the investigation publicly.

But the FBI did not inform the committees that oversee the CIA until Friday, after the news about Petraeus broke.

FBI officials have explained that the committees weren't informed, one official said, because the matter started as a criminal investigation into harassing emails sent by Petraeus' biographer, Paula Broadwell, a 40-year-old graduate of the U.S. Military Academy and an Army Reserve officer, to another woman.

The identity of the other woman and her connection with Broadwell were not immediately known, but that probe led agents to Broadwell's email, which uncovered the relationship with Petraeus, a 60-year-old retired four-star general, according to an official who spoke to The Associated Press on Saturday.

Concerned that the emails he exchanged with Broadwell raised the possibility of a security breach, the FBI brought the matter up with Petraeus directly, according to the official, who spoke on condition of anonymity because he was not authorized to publicly discuss the investigation.

Petraeus decided to quit, though he was breaking no laws by having an affair, officials said.

"He decided he needed to come clean with the American people," said Steve Boylan, a retired army officer and former Petraeus spokesman who talked with him Saturday.

Petraeus lamented the damage he'd done to his "wonderful family" and the hurt he'd caused his wife, Boylan said. Petraeus has been married for 38 years to Holly Petraeus.

"He screwed up, he knows he screwed up, now he's got to try to get past this with his family and heal," said Boylan.

Feinstein said Sunday that she has not been told the precise relationship between Petraeus and the woman who reported the harassing emails to the FBI. She said she has been told only that she was someone Petraeus "knew and was close to."

Broadwell interviewed the general and his close associates intensively for more than a year to produce the best-selling biography, "All In: The Education of General David Petraeus," which was written with Vernon Loeb, a Washington Post editor, and published in January.

The CIA did not comment on the identity of the woman with whom Petraeus was involved.

Broadwell is married with two young sons. She has not responded to multiple emails and phone messages. She'd planned to celebrate her 40th birthday in Washington this weekend, with many reporters invited. Her husband emailed guests to cancel the party.

CIA officers long had expressed concern about Broadwell's unprecedented access to the director. She frequently visited the spy agency's headquarters in Langley, Va., to meet Petraeus in his office, accompanied him on morning runs around the CIA grounds and often attended public functions as his guest, according to two former intelligence officials.

Petraeus' staff when he was overseeing the war in Afghanistan similarly had been concerned about the time she spent with their boss.

In the preface to her book, Broadwell said she first met Petraeus in the spring of 2006 while she was a graduate student at the Kennedy School of Government at Harvard.