Pattie Boyd Recalls Poignant Final Meeting with Former Husband George Harrison Shortly Before His 2001 Death

Pattie Boyd was nervous when she accepted a bit part in the 1964 movie A Hard Day's Night. Sure, she only had one line — "Prisoners!?" — but she was delivering it to the Beatles.

At the time, the 19-year-old was making a name for herself as a rising star in the modeling world, posing for haute couture fashion spreads with legendary photographers like David Bailey and John French. To date, the most screen time she'd had was a TV ad for potato chips. She assumed this audition was for just another commercial, but then she learned she'd snagged a role in a feature film alongside the four most famous men on the planet. The pressure was on.

"Initially I thought, 'I can't do this. I'm not an actress. There's no way I can do this,'" Boyd tells PEOPLE. "But my agent said to me, 'Don't worry, you've only got one word to say. Easy peasy. It'll be fine.'"

She took the leap, and that day on set in March 1964 changed her life. It was there that she met her first husband, George Harrison. Within two years they were married, but life as a Beatle bride wasn't always easy.

Boyd has opened up about their years together in her new book, Pattie Boyd: My Life in Pictures, a visual treasure trove that draws on 300 images from her personal archive. Showcasing both her dazzling memories and her formidable talent as a photographer, the collection (due out Dec. 20 in the US) is an intimate portrait of rock legends — or, as she calls them, "old friends."

Boyd inspired Harrison to write some of the most heartfelt songs, including the romantic evergreen "Something." But their marriage was unable to survive the tumult of the Beatles years and the pair began to drift apart at the dawn of the '70s. "George and I were going in different directions," she explains. "He was starting to distance himself from me." The pair amicably went their separate ways in 1974, at which point Boyd began a relationship with Harrison's close friend Eric Clapton, who'd previously tried to woo her by writing the lovelorn epic "Layla" in her honor.

Harrison's response to her new love was shockingly good-natured. "He said, 'Well, I'm glad you're going off with Eric instead of some idiot," Boyd remembers. "So he appreciated my choice!" George would jokingly refer to himself ever after as "the husband-in-law" in their presence. The threesome even celebrated Christmas together that same year. When she tied the knot with Clapton in 1979, Harrison was on hand at the reception, serenading the newlyweds with an impromptu jam alongside his old bandmates Paul McCartney and Ringo Starr.

Boyd would remain close with Harrison for the rest of his life. My Life in Pictures contains the last photo of them together, taken in the early '90s in the garden of Friar Park, the sprawling estate they'd shared during their final days as a couple.

Harrison dropped in on Boyd just a few months before his death in November 2001. Though he didn't say as much, it was obviously a goodbye. "He came with some little gifts and we played music and had some tea," she recalls. "It was lovely to see him, but I knew he wasn't well. I sensed that he wanted to see me rather than leave it too late." As they talked in her garden, Harrison noticed a few lone flowers poking through the dirt and shaking in the breeze. "The flowers are shivering," he said — an observation that always stuck with Boyd. "Only George would think flower shiver. It was so sweet." It was the last time they saw each other.

Boyd, now 78 and married to property developer Rod Weston, says she believes in soulmates — not just one, but several (if you're lucky) that come through your life. "You can meet someone and just recognize the essence of their being," she explains. "And they're always a joy to be with. Even if a year goes by and you don't see them, when you will reunite, you're still on the same page."

That was the kind of bond she shared with Harrison. "Just because things didn't work out as we planned, it didn't diminish our love for each other."