General David Petraeus, with wife Holly, at his confirmation hearing last year (Getty Images)

The sudden resignation of four-star general David Petraeus from his role as director of the CIA has revealed that he had an extramarital affair, apparently with his biographer Paula Broadwell. The indiscretion was discovered by the FBI, who had been pursuing a separation investigation—and now officials say that Broadwell sent “harassing” emails to another woman, who was so frightened she contacted the FBI for help.

According to the Washington Post, “The identity of the woman who received the e-mails was not disclosed, and the nature of her relationship with Petraeus is unknown. The officials said the woman did not work at the CIA and was not Petraeus’s wife, Holly. The law enforcement officials said the e-mails indicated that Broadwell perceived the other woman as a threat to her relationship with Petraeus.”

The NY Times adds that the recipient of the “harassing” emails was not a family member and officials say “the two women seemed to be competing for Mr. Petraeus’s loyalty, if not his affection.” The NY Post spoke to a government official who says the emails from Broadwell said things like “I know what you did,” “back off” and “stay away from my guy.”

Further, the Times reports, “When F.B.I. agents following up on the complaint began to examine Ms. Broadwell’s e-mails, they discovered exchanges between her and Mr. Petraeus that revealed that they were having an affair…”—one of the emails may have referenced “sex under the desk”—”They also discovered that Ms. Broadwell possessed certain classified information, one official said, but apparently concluded that it was probably not Mr. Petraeus who had given it to her and that there had been no major breach of security.”

Broadwell, 39, co-wrote a glowing biography of Petraeus, 60, titled, All In, and even spent a year embedded with him in Afrghanistan. However, some former Petraeus staff members said Broadwell never seemed very credible and were shocked at the access she got to Petraeus.

One told the WaPo, “My gosh, if you are going to have someone interview everyone who has ever touched you in your life, choose someone who has written a biography or at least a history book.” Further, another former staffer noted how Broadwell wore form-fitting clothes in Afganistan—”Petraeus once admonished her, through a staffer, to ‘dress down,’ a former aide recalled”—and others “grew concerned about her posts on Facebook, which they believed sometimes divulged sensitive operational details. The posts, intended for friends back home, were often playfully written and aimed at showing off her adventures in the war zone.”

Petraeus has been married to his wife Holly for 37 years. Broadwell is also married, with children; the Charlotte Observer saw a “pressure-washed” message on her driveway: “Dad ♥’s Mom.”

Broadwell had invited reporters to celebrate her 40th birthday in Washington D.C. this weekend, but the Observer notes, “Her husband emailed guests to cancel the event late Friday.” A neighbor said that he had emailed with her on Friday, to see if she needed any help: “She responded that night, saying the family was doing OK and to keep an eye on their house.”