Diane Keaton and Woody Allen’s complicated history, ‘Distraught’ (Exclusive)

Diane Keaton, who died on October 11 at the age of 79, starred in many iconic films, but only won an Academy Award for Woody Allen’s 1977 romantic comedy masterpiece Annie Hall.

“He is extremely distraught, surprised and upset,” a source exclusively tells PEOPLE about the news of Keaton’s death, adding, “It’s making him think about his own death.”

Allen, 89, and Keaton “remained friends” for nearly 60 years after sharing a romantic relationship, a source said. “He thought very highly of her.” The source said Allen was unaware of Keaton’s declining health. “No one else seemed to know. He was surprised.”

After playing Kay Adams, Michael Corleone’s tormented partner, in Francis Ford Coppola’s The Godfather (1972) and The Godfather Part II (1974), Keaton showed a lighter side in Allen’s classic film, which revolved around the complicated relationship between a struggling nightclub singer (Annie Hall) and a comedian (played by Allen).

This was a role that only Keaton could play. Allen wrote the role to highlight Keaton’s unique sensibilities and style after co-starring with her in the films Play It Again, Sam (1972), Sleeper (1973), and Love and Death (1975). Before co-starring in Hollywood, Keaton starred in the 1971 Tony Award-nominated stage version of Play It Again, Sam.

Many have speculated that Annie Hall may be based on Keaton and Allen’s relationship, and they were known to have dated in the 1960s. Around the time the film was released, she told the New York Times, “It’s not true, but there are elements of truth in it.”

Speaking to PEOPLE in 1975, Allen spoke highly of his leading lady, calling Keaton “one of the greatest natural comediennes I’ve ever seen.”

Legendary late-night host Johnny Carson offered some insight into their relationship that same year, telling PEOPLE: “I think she’s Woody’s sister. They’re both uncomfortable and withdrawn in crowds. She’s a free spirit, and that vulnerability is a good quality. She’s true to who she is, and that’s rare.”

Following the success of Annie Hall (which, in addition to Keaton winning Best Actress, the film also won Best Picture in 1978), Keaton would co-star with Allen again in 1978’s Interior, 1979’s Manhattan, and 1993’s Manhattan Murder Mystery. In the latter film, Keaton was cast at the last minute to replace Allen’s longtime collaborator and lover Mia Farrow, amid a custody battle between Allen and Farrow following the discovery in 1992 of Allen’s affair with Farrow’s adopted daughter, Soon-Yi Previn, who was about 20 years old at the time.

(Allen and Previn have been married for more than 20 years.)

Ms Farrow, who testified against Allen in 1993 as part of a bitter custody battle, claimed that in 1992 Dylan had sexually touched her and told her that he had “acted inappropriately towards Dylan”. Allen, who repeatedly denied the charges over the years, was never charged and later married Previn.

Despite the controversy surrounding Allen, Keaton remained his staunch supporter. In 2018, as Allen faced fresh backlash amid the #MeToo movement, Keaton defended her friend on Twitter, sending a powerful message of support.

“Woody Allen is my friend and I continue to believe in him,” Keaton wrote. “It might be interesting to watch that 1992 60 Minutes interview and see what you think.” She also linked to the interview in her tweet, in which he defended Dylan and Mia against their accusations.

Keaton has consistently maintained that “she did not believe that any issues[involving the allegations against Allen]would overshadow the important work he did and the work they did together,” Allen sources wrote. “So she was always there for him, and he was always grateful for that. So he always felt close.”

The source continued, “They used to talk and communicate on the phone. Every time she stood up for him, he would reach out to her and text her.”

In 2014, Keaton praised the Guardian, saying, “He’s the strongest person I’ve ever met in my life. He’s made of steel. And talk about work ethic. He’s one of the people who really taught me that you have to work hard. But he wanted to. He’s the most disciplined person I know, other than my dad.”

“But his discipline hasn’t changed, and I think he lost track of what he was doing when my father retired. This guy? He’s going to practice his clarinet, tour with his band, make one movie a year until they push him — he’s never going to stop. Who in movie history has ever done that? He’s 78 years old, he makes one movie a year, and he’s in complete control. How is that possible?”

Asked to respond directly to the child sexual abuse accusations, Keaton said, “I have nothing to say about that, other than to say that I believe my friend.”

The two have remained close ever since, and in 2017 they made a rare appearance at the 45th AFI Lifetime Achievement Awards Ceremony, where Allen was honored.

“The moment I met her, she was a great, great inspiration to me,” Allen said while introducing Keaton at the event. “I definitely owe a lot of what I’ve accomplished in life to her. I’ve been able to see life through her eyes. She’s truly an amazing person. She’s an amazing woman in everything she does.”

Keaton never married, but is survived by two children, daughter Dexter and son Duke.