Jenny Boyd has two words for anyone who ever fantasized about marrying a rich and famous rock star. “Watch out,” she said, with a laugh. “It’s not what you think.”

She should know. In the 70s, Boyd married Mick Fleetwood twice, first in a stretch between 1970 and 1976, and then, for a fraught year between 1977 and 78, each resulting in feelings of loneliness, jealousy, rage and, ultimately, a total loss of identity. “If you’re going to be with someone who’s clearly an artist, who’s deeply dedicated to what they do, then you need something that you’re passionate about,” she said. “Otherwise, you’re just an extension of someone else’s dream. Sadly, I never felt I was creative. I felt so locked inside.”

Exactly what she locked inside has finally been released in new memoir, titled Jennifer Juniper: A Journey Beyond the Muse. In vivid, anxious and sometimes hilarious prose, her book chronicles a life at once privileged by its proximity to the starriest rockers of the 1960s and 70s, and plagued by her inner feelings of anxiety and doubt.

On the enviable side, Boyd’s connections went far beyond Fleetwood Mac to bring her deep into the Beatles’ inner circle. Her sister, Pattie, married George Harrison in the mid-60s, before going on to wed Eric Clapton. Pattie published her own book about being a rock star muse in 2007, titled Wonderful Tonight, after the song penned for her by Clapton. Just as Pattie inspired that song, as well as Something, by Harrison, and Layla, by Clapton, Jenny prompted a smitten Donovan to serenade her in his fanciful 60s hit Jennifer Juniper, which lent the book its title. The Boyd sisters, as they were known at the time, also enjoyed brief, but notable, careers as models in the swinging London of Carnaby Street, where they exemplified its doe-eyed innocence and insouciant character, captured in the smart clothes of designers like Foale and Tuffin.

Despite having what Boyd called “just the right look for the time”, her insecurities surged, first over her belief that she was just an extension of her older sister, who had gone into modeling first, and then for her inability to master the gait of a proper catwalk. “When I had to do the straight modeling, it was terrifying,” she said. “It didn’t feel like me at all.”

So she wound up making her own style, dancing down the runway instead of walking. “The music they were playing was Motown, or rhythm and blues, which you just have to dance to,” she said. “I became known for that.”

Jenny, Mick and Amelia. Photograph: Sally Fleetwood

While it was already de rigueur for rock stars to date models, Boyd knew Fleetwood before she ever sat for a professional photographer. They met in school when she was 15, one year younger than he. “There was this sense of recognition,” she said. “And we had similar backgrounds. His father was a pilot, like mine, and he’d lived in a different country as a small child, as I had.”

Even so, Boyd’s childhood was far more wounding than Fleetwood’s. Her dad was scarred in battle in the second world war, which left him “disfigured and traumatized”, as she wrote in her book. He was already a distant person and his marriage to her mother was deemed “a mistake”, by both parties. When Jenny was just nine months old, her parents moved the family to east Africa, where their already shaky marriage crumbled. After her mother returned to England, with the children in tow, her mother remarried. The reception party afterwards set the stage for Jenny’s later reliance on alcohol. Though she was just five at the time, “there were two guys at the back of the hall giving me glasses of champagne over and over,” she said. “They were thinking it was funny to see this little kid completely off her head. That’s where it all started.”

Her home life was equally unbalanced, marked by threats of violence from her stepfather. “In my upbringing, there was never that support from parents that makes a child into someone who has confidence,” Boyd said.

Outside the home, her beauty attracted boys, and her connection to them brought her to the center of London’s bold new music scene. At the time she met Fleetwood, he was already playing in a band, the Chaynes, who supported the Yardbirds and the Stones, whose world became her circle. At one point, Mick Jagger told her he’d written a song for her, though he didn’t bother to mention which one. “I always wondered about that,” Boyd said, with a laugh.

Jenny Boyd. Photograph: Courtesy of Jenny Boyd

She spent time in San Francisco and later accompanied her sister and Harrison on the Beatles’ famous trip to India to visit the Maharishi in 1968 but things didn’t turn out as planned. From the start, Boyd suspected the Maharishi of having less-than-pure motives, and the whole party wound up bolting from the ashram after accusations that the guru had acted inappropriately with a young woman in their party. Today, Boyd thinks that allegation may have been “a bit of mischief”, concocted by “Magic Alex”, a man given that nickname by the Beatles for his supposed technological skills. “He was quite possessive of John [Lennon] and wanted him to go to his guru,” she said. “There was definitely some underlying stuff going on.”

Back in London, Boyd began to manage the Beatles’ Apple Boutique, sporting clothes by its design team, The Fool. There, Donovan began to see her. And though he wrote his hit song for her, they never consummated their flirtation, a decision Boyd said, was hers. “It was more like courtly love,” she said.

During this time, she had an on-again/off-again romance with Fleetwood. It wasn’t until six years after their meeting, in 1970, that they finally wed. Even at the ceremony, she described the drummer as living in a world of his own, his thoughts fixed on the band. At the time, that did make sense. The group’s star guitarist, Peter Green, had just left them, and if Fleetwood hadn’t rallied the rest to carry on, “they would not have survived,” Boyd believes. “Mick had a large vision. And he’s incredibly tenacious.”

To solidify the band, Fleetwood suggested they live together, a move that didn’t thrill his new wife. “I wanted to start a family, not a commune,” she wrote in the book.

Though the band added a woman to their ranks, the supremely talented Christine McVie (wife of bassist John McVie), she was considered by them to be “one of the guys”. The album they recorded took its name from the place where they lived, Kiln House. For its sessions, Boyd wrote all of the lyrics for the song Purple Dancer, and some of them for Jewel Eyed Judy. But she wasn’t given any credit. “Their manager wanted his band to be ‘the guys’,” Boyd said. “To have Mick’s wife have credit, he wouldn’t want that. So, he gave it to Mick.”

To promote the album, the band went on a long tour of America, leaving Boyd alone when she gave birth to their first child. Over the next few years, her loneliness ballooned, while Fleetwood’s ambition exploded. Even when the couple were together, they barely communicated. “We were both bad at that,” she said.

In her most alienated stage, Boyd had an affair with a guitarist in the band, Bob Weston, who gave her the attention her husband hadn’t. When Fleetwood found out, he fired Weston. But, soon after, Boyd dumped the guitarist and went back to her husband. “The affair I had with Bob, I felt so guilty about it,” she said. “It took me many years to get over it, because it was so against my nature. I’m a naturally monogamous person.”

Of course, Fleetwood had his own affairs, most ruinously with Stevie Nicks. “For years I didn’t talk to her,” Boyd said.

Jenny Boyd and Mick Fleetwood. Photograph: Kells Jesse

During this low period, her use of alcohol and drugs soared, as did Fleetwood’s. Her emotional isolation led her to leave her husband several times, taking their two children with her. That outraged Fleetwood’s parents as well as hers, who all viewed her as an ingrate who didn’t appreciate the rich life she’d been given. In one stretch, they banished her from seeing her children, keeping them instead with Fleetwood’s family. In one of the worst periods, Boyd sought refuge with sister Pattie and Clapton, only to find them both to be 24/7 drunks. Not only did the alcohol make Clapton verbally abusive, on one occasion Boyd claims he crawled into her bed, while her sister slept in the same house. “That was horrendous,” said Boyd.

At the same time, something her sister said explained, if hardly forgave, Clapton’s action. “She told me he had been wanting to separate us,” she said.

After divorcing Fleetwood for a second time, in the late 70s, Boyd married the journeyman drummer Ian Wallace, but that relationship fell apart for many of the same reasons her earlier one had. Only after Boyd divorced Wallace, in the 90s, did she sort out her life, axing the alcohol and drugs, going back to earn a degree in psychology and, finally, beginning what would become a long career running an addiction treatment center in England. Boyd also went on to write a book before the new one, titled Musicians in Tune, for which she interviewed 75 musicians about their creative process. For the book, she talked to Fleetwood, who she came to forgive and to form a warm friendship with. In speaking to him about their many difficult years, Fleetwood told her he “had no idea that’s what was going on with me”, she said. “I’m not surprised, because everybody was so out of it.”

While Boyd believes it hurt Fleetwood to read her book, he has endorsed it. She even managed a rapprochement with Stevie Nicks. “A few years ago, when the band were playing the O2 Arena, she wanted to see me,” Boyd said. “She apologized. I told her I had forgiven her years ago, but I really appreciate that.”

In 1997, Boyd married a non-musician, the architect, David Levitt, who is a member of the mayor of London’s design council.

These days, Boyd takes a sanguine view of everything she experienced with the band. “I saw Fleetwood Mac in Paris recently,” she said. “Standing on the side of the stage, I thought, ‘God, I love these guys.’ We’ve all been through so much together, over so many years. A love will always be there for just that reason.”