Michael Keaton is mourning his Mr. Mom costar Teri Garr, who died on Oct. 29 at age 79.
"[T]his is a day i feared and knew was coming," Keaton, 73, wrote on Instagram about Garr, who revealed in 2002 she had been diagnosed with multiple sclerosis.
"Forget about how great she was as an actress and comedienne. She was a wonderful woman. Not just great to work with but great to be around. AND go back and watch her comedic work-Man, was she great!!"
The pair played a couple in the classic 1983 comedy about Jack Butler, a married Michigan dad who struggles with domestic duties when he's laid off from his job and his wife Caroline (Garr) goes back to work. The movie, which featured Keaton in his first lead role, also starred the late Martin Mull and Christopher Lloyd.
Speaking with PEOPLE while promoting Beetlejuice Beetlejuice just weeks before Garr died, Keaton fondly recalled his time working with her.
"First of all, the first thing I'm going to talk about is the fabulous, and I mean fabulous legend, Teri Garr, how fantastic she is, and how sweet she is, and how much fun we had in this movie," he said.
"Regardless of this movie, if you look at... Just go watch Young Frankenstein, man. And she's still just so great," he added.
Keaton said he knew the script, written by John Hughes, would make a fantastic comedy.
"I remember reading the script. And I remember laughing out loud three or four times," he said. "And to most people, that seems like, 'Well, that's not much.' But ask anyone. Because the others you're smiling at or you're smiling, reading, and kind of thinking about it, or imagining it. But if something makes you laugh out loud, that's encouraging, to say the least."
Keaton was correct. Thanks to the chemistry and banter between the two leads, the movie received generally positive reviews. It earned $63 million at the box office (roughly $200 million in today's dollars), making it one of the top 10 hits of the year.
Prior to Mr. Mom, Garr made a name for herself in comedy and starred in hits like 1974's Young Frankenstein and 1982's Tootsie, for which she earned an Oscar nomination for Best Supporting Actress.
Garr died Tuesday "surrounded by family and friends," publicist Heidi Schaeffer told PEOPLE.
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