Paula Broadwell spent hours interviewing Holly Petraeus, former CIA Director’s wife, about the couple’s relationship while she was secretly carrying on an illicit affair with David Petraeus.

Paula Broadwell, 40, called Holly Petraeus “a wonderful source of information” for her research on the once esteemed army general, who resigned from the CIA Friday after admitting that he engaged in an affair with his biographer.

In her book, All In: The Education of General David Petraeus, Paula Broadwell recounted details from dozens of hours of interviews between Holly and David Petraeus in a description of how the couple met and fell in love. She described the relationship as virtually unbreakable, while at the same time, she was carrying on an illicit affair with David behind Holly’s back.

Holly Petraeus is “furious” as details of Paula Broadwell’s relationship continue to emerge, according to a former spokesman for David Petraeus.

Retired U.S. Army Col. Steve Boylan described the Petraeus family’s outrage: “His children may be grown up, but he still has to regain their trust.”

“Holly is disappointed, upset and furious… but they have been married for 37 years and I hope they can get through this.”

Steve Boylan said that David Petraeus is still living at home with his wife despite revelations of his eight-month affair with his biographer.

He also revealed that David Petraeus has contacted his former mistress – his biographer and a married mother of two, Paula Broadwell – over recent weeks, despite ending the affair four months ago.

The couple had mutually agreed to stop their illicit affair, knowing what they were doing was “wrong”. But “David and Paula were still in contact about Paula’s dissertation”.

When asked if their marriage could survive, he added: “I hope so, they are a strong couple, but every day is a challenge. All David is focused on now is saving his family.”

Col. Steve Boylan said that Holly Petraeus had been told of the affair on Thursday before he met with President Barack Obama to offer his resignation.

“She is very classy, very unassuming,” he said.

“She has established herself and her own career in her own manner.

“She’s a very lovely lady, endearing. But she is also someone I would not want to get angry at me.

“It’s those reserved, quiet types you have to look out for. But she’s a joy to be around, a very gracious and caring individual.”

Paula Broadwell spent hours interviewing Holly Petraeus about the couple’s relationship while she was secretly carrying on an illicit affair with David Petraeus

In Paula Broadwell’s book, she described Holly Petraeus as a witty head-turner.

“In the fall of 1973, Holly Knowlton was a senior at Dickinson College, a beautiful, smart and witty young woman,” Paula Broadwell wrote.

At the time, David Petraeus was attending West Point.

“On a visit to West Point one football weekend, a friend of the family had hoped to fix her up with a certain cadet to take her to the game,” Paula Broadwell wrote.

“But when he was otherwise engaged, a call was placed to the cadet brigade headquarters to find a replacement…David Petraeus. Not knowing who his blind date was, he agreed to take on this potentially sensitive mission.”

David Petraeus fell fast for Holly Knowlton, but not just for her looks and wit, according to Paula Broadwell.

The army cadet found Holly Petraeus’ high-profile military family – her father was the superintendent at West Point – “intoxicating”, Paula Broadwell wrote.

“Soon, the two would find themselves commuting to each other’s colleges whenever time allowed, sometimes braving fierce New York snowstorms to spend time together,” according to Paula Broadwell.

“Petraeus would sneak into the superintendent’s side door to visit Holly when she made the trip back to West Point.”

David Petraeus told friends that his affair with Paula Broadwell began around the time that he was appointed director of the Central Intelligence Agency in the summer of 2011 and that he cut off the relationship four months ago.

The affair was revealed by an FBI investigation into threatening emails that Paula Broadwell had anonymously sent to Jill Kelley, whom she believed to be a rival for David Petraeus’s attention.

The FBI traced the emails to Paula Broadwell and uncovered the affair, which eventually led to David Petraeus’s decision last week to resign and admit to the infidelity publicly.

In advertising her book, Paula Broadwell said she has a fierce competitive streak, which is probably what led her to email another woman that she considered her rival.

On an official Web site for her book, which has since been removed, Paula Broadwell explains: “I was driven when I was younger. Driven at West Point where is much more competitive in that women were competing with men on many levels, and I was driven in the military and at Harvard, both competitive environments.”

Just as her affair with David Petraeus was budding, Paula Broadwell went on a book tour to promote her biography of Petraeus and she heaped praise on Holly.

“As a working mother and wife, my husband works really works hard, it’s hard to find balance, you know, it’s pretty clear and Holly’s pretty clear that she’s supported him and yet they have this wonderful marriage and very established children,” Paula Broadwell said in February.

Paula Broadwell also added that she likes “teasing” the general for being “monodirectional”.

“He doesn’t like to do anything besides run and do P.T. and read and work, you know, and go out to dinner with Holly,” Paula Broadwell said.

“I don’t know if that’s a weakness, but I feel like he could have more balance and learn to relax.”