Catherine Zeta-Jones Remembers 'Darling' Father-in-Law Kirk Douglas: 'I Miss You Already'

Catherine Zeta-Jones is paying tribute to her legendary father-in-law Kirk Douglas.

The Hollywood icon died at age 103, Zeta-Jones’ husband and Kirk’s son Michael Douglas confirmed to PEOPLE Wednesday.

“To my darling Kirk, I shall love you for the rest of my life,” Zeta-Jones, 50, wrote on Instagram, sharing a black-and-white photo giving Kirk a kiss on the cheek.

“I miss you already,” she added. “Sleep tight…”

The Mask of Zorro star’s tribute to the late actor came just about two months after celebrating his 103rd birthday.

“This guy on my knee, is 103!!!!!Happy Birthday Pappy!!! I love you with all my heart. 😘❤️” she wrote on December 9, sharing a throwback photo of the duo.

Michael, 75, also shared a photo with his dad on his milestone birthday — which happened to be the same day he received a Golden Globe nomination for The Kominsky Method — writing, “Happy birthday Dad! You are a living legend and your entire family sends you all the love in their hearts! #KirkDouglas #103.”

Shortly after that first post, he shared another picture with his dad, who he said was “proud” of his nomination.

“12.9.2019 what a great day! Thank you to the HFPA for the @GoldenGlobes nomination, and for making my Dad proud on his 103rd birthday! #TheKominskyMethod,” he wrote alongside the photo.

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Michael confirmed to PEOPLE that his dad had died at 103 on Wednesday.

“It is with tremendous sadness that my brothers and I announce that Kirk Douglas left us today at the age of 103,” the statement read. “To the world, he was a legend, an actor from the golden age of movies who lived well into his golden years, a humanitarian whose commitment to justice and the causes he believed in set a standard for all of us to aspire to.”

“But to me and my brothers Joel and Peter he was simply Dad, to Catherine, a wonderful father-in-law, to his grandchildren and great grandchild their loving grandfather, and to his wife Anne, a wonderful husband,” the Behind the Candelabra star continued.

“Kirk’s life was well lived, and he leaves a legacy in film that will endure for generations to come, and a history as a renowned philanthropist who worked to aid the public and bring peace to the planet,” the statement said.

“Let me end with the words I told him on his last birthday and which will always remain true,” he concluded. “Dad- I love you so much and I am so proud to be your son.”

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In addition to his more than 92 acting credits, Kirk is remembered for breaking the Hollywood blacklist when he hired screenwriter Dalton Trumbo to write the 1960 epic Spartacus, which Kirk executive produced and starred in.

“It was such a terrible, shameful time,” Douglas told PEOPLE about the purge of alleged Communist sympathizers in the entertainment industry during the 1940s and ’50s. “Dalton was in prison because he refused to answer questions, so I decided, the hell with it! I’m going to put his name on it. I think that’s the thing I’m most proud of because it broke the blacklist.”

He is survived by his wife of 65 years, Anne, and his sons Michael, Joel, and Peter.