Paula Broadwell, the former CIA director’s biographer and reported lover, allegedly sent a number of threatening messages to Jill Kelley, a 37-year-old civilian who organised parties for the US military, who became frightened and turned to the FBI for help.
As federal agents began to review the emails they quickly realised that the head of America’s top intelligence agency was involved in a sexual affair with a married woman and began an investigation to see if there had been any breach of national security.
Although the emails, believed to have been sent anonymously by Mrs Broadwell, 40, were said to have contained hints at classified information, the FBI concluded that there was no security threat and that they were instead looking at a case of lover’s jealousy.
According to The New York Post, Mrs Broadwell, a mother of two, told Mrs Kelley: “I know what you did” and warned her to “back off” from the 60-year-old former general.
Mrs Kelley occasionally volunteered to organise social events for the the US military in Florida at the time Gen Petraeus was running US Central Command and based in the same state.
“We and our family have been friends with Gen Petraeus and his family for over five years. We respect his and his family’s privacy and want the same for us and our three children,” Mrs Kelley said in a statement.
Photographs showed the Petraeuses and the Kelleys posing together at a pirate-themed festival in 2010 and ABC News reported that the families had spent Christmases together.
It is not clear why Mrs Broadwell would believe that the mother-of-three, posed a threat to her relationship with the general.
Mrs Broadwell did not respond to The Daily Telegraph’s attempts to contact her at her home in North Carolina.
Gen Petraeus has made no public statement since his abrupt resignation on Friday, when he announced that he was stepping down because he had shown “extremely poor judgment by engaging in an extramarital affair”.
Steve Boylan, a former army officer and close confidante of the decorated commander, said Gen Petraeus told him over the weekend that he felt he needed to “come clean with the American people”.
“He screwed up, he knows he screwed up, now he’s got to get past this with his family and heal,” said Mr Boylan.
That narrative, however, seemed to contradict the account given by government officials to media outlets, which claims that Gen Petraeus resigned only after being confronted by FBI agents two weeks ago and was then urged to step down on Tuesday by James Clapper, the Director of National Intelligence.
Gen Petraeus met his wife of 37 years, Holly, in the mid-1970s while studying at West Point military academy, where her father was the school’s superintendent.
He has often publicly praised her devotion as she stayed at home to raise their two children while he spent long postings abroad.
His decision to accept the CIA post meant that the couple were finally reunited and moved into a rented home in northern Virginia, where the basement was renovated to fit secure communications equipment.
According to the Wall Street Journal, the Broadwell affair began in August 2011 just as Gen Petraeus was preparing to leave the military and continued until a few months ago.
Despite the political fallout, the CIA is not expected to conduct an internal investigation and senior figures in the agency are reported to be satisfied that Gen Petraeus’s infidelity did not lead to an intelligence leak.
Washington remained stunned over the weekend as more details emerged about the tawdry end to the career of one of America’s most celebrated soldiers.
Barack Obama praised Gen Petraeus, who served as commander of international forces in both Iraq and Afghanistan, saying that his service had “made our country safer and stronger”.