"The whole episode is incredibly painful," she told CBS News correspondent Anthony Mason.
The daughter of a British Air Force pilot, Boyd was a 20-year-old model in 1964 when her agent told her to report to London's Paddington Station to play a bit part in the Beatles film "A Hard Day's Night." It was a role that changed her life forever.
Boyd, who played a schoolgirl on a train, said just one word in the movie: "Prisoners." That was it. But she caught the eye of George Harrison, who made sure he sat beside her at lunch.
"And I thought he was really pretty gorgeous," she said.
Out of loyalty to a boyfriend, she told Harrison she already had a date.
"My one girlfriend said, 'Are you completely mad? Dump the boyfriend immediately," she said. "So I did."
Harrison and Boyd became one of mod London's most glamorous couples. He was the shy Beatle, and she appeared on the cover of British Vogue. When they married in 1966, Boyd writes: "I was so happy I thought I might burst."
It was Boyd who introduced Harrison to meditation, which led the Beatles to India in 1968. She recently found her pictures of the trip.
"And that was, I think probably the last time that George was terribly peaceful and happy and calm," Boyd said.
But "after India," Boyd writes, "our lives and our relationship seemed to fall apart." With the sudden death of their manager, Brian Epstein, the Beatles had to become businessmen.
"And there was an awful lot of tension within the band and I think what was happening is that George was bringing that home," she said. "It definitely put stress on our relationship."
Harrison meanwhile had become close friends with another musician. Eric Clapton began showing up at the Harrison home frequently. Boyd could sense right away that Clapton was attracted to her and Harrison had started to become openly flirtatious with other women. Boyd thought it was something she just had to put up with. His spirituality was also making him increasingly remote.
But Clapton showed her the attention Harrison wouldn't. He wooed her obsessively one day, inviting her to his band's London apartment to play her a song.
"It was the most incredible song," she said. "He played 'Layla.'"
A song about a man obsessed with an unavailable woman. There was no mistaking "Layla" was Boyd.
"It's a pretty enticing song, you know? It's deeply seductive," she said. "I mean, you know, it's the most incredible song. And he sings it so — it's so heartfelt. It bowled me over."
Later that evening, at a party, it all came out when Harrison discovered Boyd and Clapton talking.
"And Eric said, 'I have to tell you something. I'm in love with your wife.' And I thought, 'Oh no!' I just wanted the ground to open up," Boyd said. "This is not a situation I was happy to be in. Anyway, George was furious and said, 'Well, go off with him if you want.' And I said, 'No, I'm coming home with you.'"
Boyd would stay in the marriage for three more years. The final straw was the discovery that Harrison was having an affair with a close friend.
In the first draft of her manuscript, Boyd discretely chose not to mention the name of the woman, whom she described as "the wife of one of our closest friends." But as she was finalizing the book, she called Ringo Starr to ask his advice and consent because, she now acknowledges, the woman Harrison slept with was Maureen Starr, Ringo's wife.
"She was the last person I would have expected to stab me in the back," Boyd writes, "But she did." The marriage was over.
"I thought that there was no room for me, in this ludicrous situation we'd all found ourselves in," she said. "Everyone behaving badly. You know, truly it was a mess!"
So in 1974, she left George and moved in with Eric. Remarkably, when they were married three years later, George attended the wedding party. And Clapton wrote another hit song about his new wife, "Wonderful Tonight."
But the marriage was anything but wonderful. Clapton began drinking heavily — two bottles of brandy a day. Living with him was "ghastly," Boyd said. Then Boyd, who'd tried unsuccessfully to have children, learned Clapton was about to have a baby by another woman.
He told her over dinner. "I just felt as if I'd been stabbed in the heart," she said.
Clapton even asked Boyd to help raise the boy, Connor, who would later die in a tragic fall. But it was a concession Boyd couldn't bring herself to make.
"I felt if I were to accept it, I would be destroying myself," she said. "And I would therefore have to leave."
So at 43, she was suddenly alone and only realized how lost she was when she contacted an old friend.
"And I said, 'Oh Amanda, hi. It's Pattie. I used to be Pattie Boyd.' And she said, 'You still are,'" Boyd said. "Oh, I was still, I suppose, connected with the idea of, 'Well, if I'm not Mrs. Eric, who the hell am I?' I'd lost my identity."
In time, she found it again through her love of photography. Pattie had always taken snapshots. Now she began taking pictures more seriously. And the model who'd started her career in front of the camera became an accomplished professional behind it. Later this week, an exhibition of her work will open at the Morrison Hotel Gallery in New York.
She made peace with Harrison years ago. When he died in 2001, "I felt completely bereft," she writes. "I couldn't bear the thought of a world without (him.)"
And a now-sober Clapton remains a friend. She still loves "Layla."
"It doesn't hurt," she said. "I'm beyond that. But I know it was for me. I like that."