David Petraeus has admitted to close friend James Shelton that he “screwed up royally” over the affair with his biographer Paula Broadwell – and confirmed for the first time that his wife is standing by him.

In his most frank comments on the scandal, David Petraeus said that he had created “enormous difficulty” for Holly Petraeus but revealed that she has not kicked him out.

In a letter David Petraeus said that Team Petraeus will survive and that he is “incredibly fortunate” to be married to such a forgiving woman.

He also addressed his resignation for the first time and wrote: “I paid the price (appropriately) and I sought to do the right thing, at the end of the day.”

The letter was sent on November 20 to his close friend of three decades, retired Brigadier General James Shelton, who considers himself a father figure to him.

Brig. Gen. James Shelton blamed biographer Paula Broadwell for the affair as Petraeus was the “innocent one when it came to relationships”.

He also claimed that she is a “savvy woman” who knows a lot more about matters of the heart than David Petraeus, who has spent the bulk of his life in the military and has been married for 37 years.

David Petraeus’ letter appears to confirm reports that his wife is “furious” at him over his behavior, which came to light earlier this month when in a statement admitted he had had an extra-marital affair and quit as head of the CIA.

The New York Times has reported that he has resigned himself to being “in the doghouse” for at least a year and now passes the time sitting around his home emailing friends.

David Petraeus, 60, and his wife Holly spent Thanksgiving together trying to rebuild their shattered marriage and regain the trust of their two grown up children at their home in Arlington, Virginia.

Paula Broadwell, 40, did that same with her husband Scott and their two young sons at their mansion in Charlotte, North Carolina.

David Petraeus has admitted to close friend James Shelton that he screwed up royally over the affair with Paula Broadwell

The letter David Petraeus sent to Brig. Gen. James Shelton, a Vietnam Veteran who fought with the famous Black Lion Battalion, was on Four Star General letterhead and had the post mark from the PO Box in Arlington, that he uses for correspondence.

It began by thanking Brig. Gen. James Shelton for the sending him some pictures of his own family and a note which said he still had faith in him.

It read: “I screwed up royally. I paid the price (appropriately) and I sought to do the right thing, at the end of the day.

“Team Petraeus will survive though have obviously created enormous difficulty for us. Holly is however once again demonstrating how incredibly fortunate I was to marry her.”

Brig. Gen. James Shelton, who has been awarded three Bronze Stars for bravery, said that he still thinks that David Petraeus is the best officer has ever seen – even if he is a love rat.

In his opinion the resignation was an “overreaction” for “human things he got involved with”.

James Shelton said: “I never knew David as being a woman chaser – he never gave a damn about anybody other than Holly.

“It never entered my mind that he would get involved with anybody else.

“Paula was more savvy than Dave about the nature of the things that they got involved with.”

General James Shelton explained that Paula Broadwell interviewed him whilst doing research for her biography of David Petraeus, titled All In.

He said that Paula Broadwell was “very persuasive” and managed to get him to talk about his friend on the phone without having to meet in person.

Brig. Gen. James Shelton, 76, said: “She was a beautiful woman, very intelligent and if David would say something she would know what he was talking about.

“They were both West Point Academy graduates, that’s what put them together. She had a lot of the qualities that he had.

“She’s also a savvy woman. She’s not a kid. In a lot of ways I think she knows more about the world than Dave – I’m talking about sex.

“I don’t think Dave ever thought about that too much, he only thought about the Army and gave it everything he had.

“When he got close to her it became something new and different than what he had with his wife

“I don’t believe he had any relationships with anybody else (apart from Broadwell).

“He was the innocent one when it came to relationships. It wasn’t his bag. He was a soldier. He just wasn’t involved with it.”

James Shelton however said that alarm bells rang in his mind when Paula Broadwell told him that she was going to Afghanistan to “learn how Dave operated”.

He said: “I thought that because he was over there (Afghanistan) she might have been the only outlet he had for any kind of recreation, if you get what I mean.

“He’s a human dynamo, he works all the time and she was always following him around.

“I think Paula Broadwell was in love with him. I could see it happening.

“I could see that he has so many qualities that any woman with any sense would say: <<Boy! This guy – there doesn’t seem to be a better man than this around>>.”

Brig. Gen. James Shelton, who lives in Cape Haze, Florida, first met David Petraeus in the 1970s when they were serving together in Erzurum, Turkey when Petraeus was a lowly second lieutenant in the 173rd Airborne Divison.

James Shelton said: “I walked into a tent with a bottle of Ballantine whiskey that I’d stashed in my spare boots.

“I opened it and asked if anybody wanted some, and I’m pretty sure Dave was among those who said yes, so I served it in canteen cups.

“Even then he was so interested in what I had to say. He was asking me questions about everything – I liked the cut of his jib straight away.”

They met again when they served together in the 24th Infantry Division at Fort Stewart, Georgia, and stayed in touch ever since.

In one assessment of David Petraeus when he was just a captain, Brig. Gen. James Shelton described him as the “finest officer I have ever known”.

He said: “I regard David Petraeus as one of my sons – and I have three others. I feel like a father figure to him. I served in the army for 27 years and he was the best officer bar none.

“He is a giant of a man.”

David Petraeus’ letter in full

“Dear Jim (if I may)

I can’t thank you enough for your note, kind words and support. I can’t tell you how much it all meant.

I screwed up royally. I paid the price (appropriately) and I sought to do the right thing, at the end of the day.

Team Petraeus will survive though have obviously created enormous difficulty for us. Holly is however once again demonstrating how incredibly fortunate I was to marry her.

Beyond that thanks for sending me the photos and various items you did. It was good indeed to recall some of the good guys and the good days. Great stuff.

Again, many thanks and all the best.

ATW [All The Way – a military term]”