Al Pacino is breaking his silence on the death of late costar Diane Keaton.

The Heat star, who acted alongside Keaton in all three Godfather movies and dated her in real life, penned a tribute to his former partner and collaborator for Deadline Hollywood on Thursday following her death from pneumonia at age 79 on Oct. 11.

“I am deeply saddened by Diane Keaton’s passing,” Pacino’s statement began. “When I first heard the news, I was shaken. Diane was my partner, my friend, someone who brought me happiness and on more than one occasion influenced the direction of my life.”

The actor said that although more than three decades have passed since the end of their romantic relationship, he still feels a connection with Keaton.

“The memories remain vivid, and with her passing, they have returned with a force that is both painful and moving,” Pacino wrote. “She lived without limits, and everything she touched carried her unmistakable energy. She opened doors for others, inspired generations and embodied a once-in-a-lifetime gift that radiated through her work and her life.”

Pacino went on to praise Keaton’s acting abilities. “On screen, she was magnetic — lightning and charm, hurricanes and tenderness,” he wrote. “She was a wonder. Acting was her art, but it was only one of the many ways she expressed her imagination and creativity.”

The Dog Day Afternoon star concluded, “People will miss her, but more than that, they will remember her. She left a mark that cannot fade. She was unstoppable, resilient and above all, deeply human. I will always remember her. She could fly — and in my heart, she always will.”

Pacino and Keaton met on the set of the first Godfather in 1971. In the film (and its sequels), Keaton portrayed Kay Adams-Corleone, the wife of Pacino’s Michael Corleone. Keaton told PEOPLE in 2017 that she “had a crush” on Pacino during production of Francis Ford Coppola’s first crime epic.

Diane Keaton and Al Pacino in ‘The Godfather Part III’.Emilio Lari/Paramount/Kobal/Shutterstock

The two actors later began dating, and shared an on-again, off-again relationship that lasted until 1990. “I was mad for him. Charming, hilarious, a nonstop talker,” Keaton told PEOPLE. “There was an aspect of him that was like a lost orphan, like this kind of crazy idiot savant. And oh, gorgeous!”

Keaton reportedly ended the relationship in 1990 following the production of The Godfather Part III.

The two actors maintained a mutual respect and admiration after their relationship ended, and Pacino paid tribute to his former costar when she received the AFI Lifetime Achievement Award in 2017.

“You’re a great artist,” Pacino told Keaton at the ceremony after sharing his favorite memories with the actress. “I remember it, and I love it, and I love you forever.”