King Charles felt ‘unbearable emptiness’ after Princess Diana’s death

King Charles was "shattered" when he learned that his ex-wife, Princess Diana, had died in a car accident.

The glamorous Princess of Wales passed away on Aug. 31, 1997. At the time, the 36-year-old was being chased by paparazzi in Paris. Her companion, Dodi Fayed, and their chauffeur, Henri Paul, also perished in the crash.

"When he was first told over the phone that Diana had died, Charles, according to an eyewitness, "howled like a wounded animal,’’ Christopher Andersen, author of "The Day Diana Died," told Fox News Digital.

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The former Prince Charles was "shattered" over the news of Princess Diana's tragic death, author Christopher Andersen told Fox News Digital. (Tim Graham Photo Library via Getty Images)

"Later, after he rushed from Balmoral Castle in Scotland to Paris to bring her back to England, Charles nearly passed out when he first viewed her body," he shared. "A nurse who was standing in the room told me he reeled back and looked as if he had been ‘struck by an unseen force.’ Considering how epic their marital battles had been, people were surprised at Charles’ reaction. He was devastated by Diana’s death, perhaps to a degree that surprised even him."

"Charles was shattered," Andersen added.

Christopher Andersen's book, "The Day Diana Died," is available in bookstores. (Blake Publishing)

Andersen’s statements came shortly after a letter written by the former Prince Charles to his friend was sold at auction for $2,000. In it, Charles detailed the "unbearable emptiness" he felt four months after Diana’s death, the U.K.’s DailyMail reported.

"When he was first told over the phone that Diana had died, Charles, according to an eyewitness, ‘howled like a wounded animal.'"

— Christopher Andersen, author of "The Day Diana Died."

In a letter that recently sold at auction, King Charles wrote about the "unbearable emptiness" he felt four months after Princess Diana's death. (Jayne Fincher/Princess Diana Archive/Getty Images)

Andersen noted that in Diana’s final months, the exes finally put aside their differences for the sake of their sons, Prince William and Prince Harry.

"In the months before Diana’s death, she and Charles decided to put their bitterness behind them and become, in her words, ‘very best friends,’" Andersen explained. "A close confidant of Diana’s told me that ‘her love for Charles never really died.’ Diana even grudgingly admitted that the love and devotion Charles and [his mistress] Camilla had was something to be admired."

During the final months of Princess Diana's life, she developed a warm friendship with her ex-husband for the sake of their two sons. (Getty Images)

"Charles and Diana wrote, surprisingly, affectionate notes to each other," said Andersen. "On the eve of Diana’s death, Charles dashed one off to her that began ‘My dearest Diana’ and ended with ‘Lots of love, Charles.’"

She never received it.

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Princess Diana was killed in a car crash in 1997. She was 36. Her companion Dodi Fayed and chauffeur Henri Paul also died. (Tim Graham Photo Library via Getty Images)

Behind palace doors, Charles was "swept up in a whirlwind of emotion" after learning what happened to Diana.

"The mother of his two young sons had been killed in a horrific car crash," said Andersen. "She also happened to be the most idolized woman in the world. Charles had to battle his mother, the queen, and the entire establishment of the monarchy to ensure that Diana was given the kind of funeral she deserved."

Diana received a ceremonial funeral that was attended by 2,000 people. It was watched by over 2 billion people worldwide.  

From left to right, Prince William, Prince Harry and the former Prince Charles stand outside Westminster Abbey at the funeral of Diana, the Princess of Wales, on Sept. 6, 1997. (Anwar Hussein/WireImage/Getty Images)

As Charles grieved, Diana’s rival Camilla Parker Bowles became "the target of death threats."

"She had to go into hiding until things calmed down," said Andersen. "[And] as loving a father as Charles – and even though he was heartbroken over Diana’s tragic death – he took the time-honored stiff upper lip approach. Diana’s boys were never given grief counseling of any kind. William and Harry were famously forced to walk behind their mother’s coffin through the streets of London teeming with a million weeping spectators – what their uncle Earl Spencer later described as ‘a tunnel of grief.’"

"Both William and Harry have never fully come to terms with their mother’s death," Andersen shared. "And in a sense, they have yet to emerge from that tunnel of grief."

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Christopher Andersen said Camilla Parker Bowles, Prince Charles' mistress, went into hiding after receiving death threats following Princess Diana's passing. (Mathieu Polak/Sygma/Sygma via Getty Images)

After Diana was laid to rest, Charles would still be haunted by the memories – and legacy -of his ex-wife.

"It seemed to Charles that now he would never be able to marry his longtime mistress," said Andersen. "At every turn, it seemed that Charles was thwarted by the memory of Diana. After Diana’s death, it took eight years for Charles to convince Queen Elizabeth II to allow him to marry Camilla – and then only after he promised that Camilla would never be known as queen. In the minds of millions, this was the title that rightfully would have gone to Diana had Camilla not wrecked Diana’s marriage to Charles."

"Of course, Charles broke that promise… and crowned Camilla queen," said Andersen.

King Charles and Queen Camilla were crowned on May 6, 2023, in London. (Christopher Furlong/Getty Images)

Charles ascended to the throne upon the death of his mother. England’s longest-reigning monarch died in 2022 at age 96. Charles and Camilla married in 2005 and were crowned in May 2023.

"Charles may have confessed to feelings of ‘unbearable emptiness’ four months after Diana’s death, but it wasn’t that long before he began to resent the persistent shadow she cast over everything he did," Andersen claimed. "After a quarter-century, Charles and Camilla still must endure comparison with the incomparable Princess Diana."

Today, the king is battling an undisclosed form of cancer. Andersen claimed that his illness had put the 75-year-old "in a reflective mood."

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King Charles is battling an undisclosed form of cancer. (Jonathan Brady - WPA Pool/Getty Images)

"I’m sure his memories of Diana – both the positive and the negative – are always there, lurking in the background," said Andersen. "She was a larger-than-life figure who grew even larger in death. King Charles spent years shadowboxing with the ghost of Diana."

Andersen previously told Fox News Digital it is likely that Charles has had regrets about his marriage to Diana over the years.

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"To understand just how heartbreaking Diana's marriage to Charles was, you have to go back to the beginning," Andersen explained. "Just as Kate Middleton and millions of other girls put pinups of William and their bedroom walls and dreamed of marrying the handsome prince, Diana and her generation fantasized about marrying [the former] Prince Charles. Diana was only 19 when she got engaged to Charles, and even then it was pretty clear that she was in love with him, but that he was still in love with Camilla.

Prince Charles and Lady Diana Spencer pose for photographers at Buckingham Palace after the announcement of their engagement. (© Hulton-Deutsch Collection/CORBIS/Corbis via Getty Images)

"During the TV interview right after the engagement, Charles uttered his famous ‘whatever in love means’ when asked if he loved Diana. Diana, on the other hand, didn't hesitate to say she loved him. There may have been moments when Charles wrote tender words to his Diana, but their marriage was pretty much a nightmare for both from day one."

"There was one brief time during Diana's second pregnancy when they became truly close," Andersen continued. "Diana would say it was the closest they had ever been or ever would be – but that all blew up as soon as Harry was born. Charles, who had hoped for a girl, blurted out ‘Oh, God, it's a boy. And he even has red hair.’ Diana said ‘at that moment something inside me closed off.’

Prince Charles and Princess Diana married in 1981. Their divorce was finalized in 1996. (Getty Images)

"Charles undoubtedly regrets that he ever allowed himself to be bullied by his father Prince Philip into marrying Diana – although that would, of course, have meant that William and Harry never would have existed. The sad truth is, Camilla was the love of Charles' life all along, and Diana knew it."