Tragedy of John and Carolyn: New book reveals surprising truth about doomed Kennedy marriage

John F. Kennedy Jr. had a lot on his mind. The 33-year-old law school grad had recently quit his job at the district attorney’s office and was trying to start his own magazine.

His mother, Jacqueline Kennedy Onassis, and his best friend, cousin Anthony Radziwill, were diagnosed with cancer in the same month. And he was in a tumultuous relationship with Daryl Hannah, the sultry star of the mermaid movie “Splash” and the daughter of a billionaire.

Yet, Kennedy could not stop thinking about Carolyn Bessette, a 28-year-old blonde who worked in fashion.

He had met her about a year and a half ago and had dated her on and off — mostly off — since then. But he admitted to an old friend that she was “having a heavy effect on him.”

“Well, she’s not really anybody,” he said when this pal pressed him for more details. “She’s some functionary of Calvin Klein’s … She’s an ordinary person.”

Bessette was not rich, not famous, not from an esteemed family nor Ivy League school. Yet this “ordinary” woman ended up snagging JFK Jr., America’s prince, the second son of President John F. Kennedy and First Lady Jackie and — per People magazine — the “sexiest man alive.”

They married in 1996. Their wedding, on a remote island off the coast of Georgia, was like something out of a fairy tale.

Except, as Elizabeth Beller writes in her new book, “Once Upon A Time: The Captivating Life of Carolyn Bessette-Kennedy” (Gallery Books, out now), it was more like a nightmare.

The tabloids dubbed Bessette an “ice queen,” “gold digger,” “coke head,” and “cheater.” The paparazzi hounded her, yelling obscenities at her as she left the Tribeca loft she shared with hubby “John John.”

She went on antidepressants; she was scared to leave the house.

Even after the couple’s tragic death in a plane crash in 1999, Bessette remained an elusive, distant figure. At best, she was exalted as a ‘90s fashion plate, thanks to her minimalist chic.

At worst, she was blamed for her husband’s untimely demise: Their ill-fated plane was supposedly delayed because she made her pedicurist change her nail polish three times.

In fact, Beller reports, she got to the airport at the same time as her husband and sister Lauren, who also perished in the crash.

“There seemed to be a need to deprive her of nuance and humanity,” writes Beller in the introduction. “As though she were required to play a villain role in a larger cultural narrative.”

“Once Upon a Time” aims to paint a more flattering portrait.

“I wanted to recount Carolyn’s story in a way that situated her at the center of her own narrative,” Beller writes. “When she appears in volumes of Kennedy literature, it is often as a sidebar without empathy, compassion or desire to understand who she really was. It’s time she got her due.”

Carolyn Bessette was born Jan. 7, 1966, the youngest of three girls. Her parents divorced when she was 8, but her schoolteacher mother remarried a few years later, and the family moved from middle-class White Plains, NY, to tony Greenwich, Conn.

Bessette studied education at Boston University, but landed a job assisting VIP clients at Calvin Klein after graduation.

One of those clients was JFK Jr. The two met during a fitting in 1992. He was charmed by her poise and wit. He left with several suits and her number.

The romance was rocky from the start. He invited her to a gala dinner — and then showed up with another woman.

Another time, he arrived two hours late to dinner, and she threw a glass of wine in his face.

He broke up with her after he received a letter from a friend claiming Bessette was a “user” and “partier” who “dated guys around town” and was “out for fame and fortune.” (He rekindled his romances with Daryl Hannah and model Julie Baker; she rebounded with her ex, a hunky Calvin Klein model.)

“Carolyn was upset, but not despondent,” one of her friends tells Beller about that incident. “She also knew, deep down, that this would not be the end. John was a prize, and Carolyn had her eye on the ball.”

He came crawling back in earnest after the death of his beloved mother.

Bessette, Beller writes, was the only one who could assuage his grief, and yet she remained “irked” that her boyfriend never introduced her to Jackie.

In fact, Kennedy once squired Bessette out the side door of a restaurant when he spotted his mother across the room. “Does he think I’m blind?” Jackie later asked a friend.

Bessette’s own mother, by the way, wasn’t entirely keen on her daughter’s fair-weather beau. “He’s sweet, but that entire scene is too much drama,” she said after she met him.

Still, they were drawn to each other. They got a dog; she moved into his loft. She consulted on his magazine “George.” He proposed to her in July of 1995. She got blonder, thinner, more chic.

She quit her PR job at Calvin Klein because of the attention she attracted from the paparazzi — especially after the press filmed a big fight between her and “John John” in Washington Square Park.

“It’s like I am a prey animal,” she told a friend about the constant cameras. “They are everywhere … I’m not sure I can do this.”

The problems only intensified after the wedding. Kennedy had a cordial relationship with the press. He had grown up in the limelight and knew how to handle them.

He sympathized with his wife, but he also couldn’t entirely understand her refusal to give them a smile and just go on with her life.

“I hate those bastards. I’d rather scream and curse them,” Bassette told a friend. Her refusal to engage attracted more attention. It got so bad that she once spat on a female fotog who was pursuing her. When Princess Diana died in a car crash — after being chased by the paparazzi — Bessette was, Kennedy said, “really spooked.”

“John and Carolyn were woefully undermanaged for their outsize life,” a friend told Beller. “They needed aides-de-camp. They needed security. And they should probably have moved away from that building.”

But they didn’t. Instead, Bessette shut herself inside: a princess trapped in her modern castle. Kennedy confessed to friends that he didn’t think their marriage could last, that his wife refused to have sex with him. He was photographed with a former flame at a hotel where he sometimes spent the night after marital spats.

As for the drug accusations, Beller’s sources say that Bessette barely even drank wine.

Kennedy — against nearly all of his family members’ wishes — had begun taking flying lessons years before.

He was an adrenaline junkie, and eventually bought himself a six-seater plane. Bessette largely refused to fly with him unless he had a copilot. Yet, in July 1999, she and her sister agreed to have Kennedy fly them to Cape Cod for a wedding. They never made it.

Days later, a bottle of Bessette’s antidepressants washed onto the shore.

“We are left to wonder what form the life of beautiful, captivating Carolyn would have taken, had it not been cut so short,” Beller writes. At the time of their death, Bassette and Kennedy were in couples therapy. She had talked about maybe going into psychology, or doing documentary films. Things seemed to be looking slightly up.

Yet, Bessette herself seemed to know she couldn’t quite cut it.

“If I don’t do something soon,” she half-joked to a friend, “I’m going to end up in a trailer park screaming, ‘I used to be married to JFK Jr.’”