JFK Jr., Carolyn Bessette's Lives and Last Moments Remembered

In the course of three terrible weeks in 1999, Carole Radziwill lost the three people closest to her.

Her best friends John F. Kennedy Jr., and his wife, Carolyn Bessette, perished in a plane crash, and her husband Anthony Radziwill died of cancer.

In her new memoir, "What Remains: A Memoir of Fate, Friendship, and Love," Radziwill describes her journey from working-class girl to a member of America's royal family, the Kennedys. The book offers a rare intimate look at JFK Jr., his wife, and others in the notoriously private family.

Bright Beginnings

In the early 1990s, Carole DiFalco, whose family once lived on food stamps, was working at ABC News, when she met and began dating Anthony Radziwill, the son of a Polish prince and nephew of President John F. Kennedy.

Almost from the beginning, tragedy loomed. A lump was discovered in Anthony's stomach, and he was diagnosed with a rare cancer called fibro sarcoma, which is almost always fatal. Over the next five years he would endure five rounds of chemotherapy, dozens of surgeries and six radiation treatments.

Despite Anthony's cancer, the couple married in 1994, with John F. Kennedy Jr. as best man. It was, Radziwill told ABC News' 20/20, like a scene out of "The Great Gatsby."

'Like Brothers'

Radziwill describes the relationship between her husband and John F. Kennedy Jr. as "like brothers." And she recalls meeting Carolyn Bessette, when Kennedy brought her out to their summer house in the Hamptons.

Bessette made a quick impression, Radziwill said. "She's quite striking, you know — blonde and 10 stories high. And, and I thought, 'Oh, this is, this is not a friend,'" she told ABC. Radziwill said she and Bessette bonded quickly, however, because they shared a feeling of being outsiders in the famous family.

"Without a doubt. I think she recognized it in me immediately and I recognized it in her," she said.

Still, she continued to feel like an outsider among the Kennedys. Her relationship with Anthony's mother, Lee Radziwill, was never warm and it was even frostier with JFK Jr.'s sister, Caroline Kennedy Schlossberg, she said.

In her memoir, she writes that Caroline was cool to any thought of John marrying Carolyn Bessette.

The two women were "very different," Radziwill said. "Carolyn was very impulsive and affectionate and funny and they just never could quite find that common ground," she said.

Missing from Radziwill's book, however, is any mention of the marital problems between John and Carolyn that were widely reported before they died.

She thinks the stories could have been spurred by the couple's decision to go to marriage counseling. "But they went to marriage counseling because they loved each other and they were determined to make their relationship work," Radziwill said.

Radziwill said she doesn't read the stories about alleged extramarital affairs and drug use. "I don't read those stories. In all the time that I knew them -- and I was very close to her -- I never saw them do drugs, ever," she told ABC News.

Painful Last Days

The summer of 1999 was difficult for all of them, Anthony was dying and Carole says that she, John and Carolyn were holding their breath. In early July, a doctor told Carole her husband had only weeks to live. John, she said, pleaded with her to prepare Anthony for the end.

But tragedy would strike John and Carolyn before cancer would take Anthony's life.

On July 16, 1999, Carole and Anthony were waiting on Martha's Vineyard waiting for John and Carolyn to arrive for the weekend. That evening, John's single engine plane was to fly to Martha's Vineyard and drop off Carolyn's sister Lauren then take off for Hyannis to attend the wedding of one of John's cousins.

Radziwill said Carolyn called her from the airplane before they took off.

"She was just calling to say that she was on her way. Then she said, 'I love you,' because we always ended our conversations [with] I love you. And I didn't say it back, and it always bothered me. … You remember the last thing you say to your best friend," she said.

When their plane failed to land on time, Radziwill started calling airports around the region, but there was no sign of them.

"By 2 o'clock I called the Coast Guard. It was the last thing, there was nothing left to do," she said.

She spoke to John's family and finally she called Bessette's mother.

"That was really the most difficult call. She said, 'Was anyone else with them?' I just was devastated because then I thought I have to tell her now that not only was Carolyn in the plane but Lauren was in the plane, and I just thought this is too much for any mother to bear," she said.

Her response was agonizing. "She screamed. She didn't say anything, she just screamed," Radziwill said.

Moments later, Anthony walked into the kitchen and saw all her notes. He knew his best friend was missing.

"It was heartbreaking for Anthony. I mean, I couldn't imagine anything crueler to have happened to him. To see John die two weeks before he ends up dying. It's just the cruelest of ironies," she said.

The little boys who spent nearly 40 years playing together, growing together, died just days apart. A few weeks after the crash, Anthony made his last trip to the hospital and passed away.

"The love, the happiness, the joy, the heartbreak, the sorrow. It all remains," Radziwill said. "And I think I'll carry that with me forever," she said.