Michael Keaton mourns ‘Wonderful’ Mr. Mom costar Teri Garr

Michael Keaton mourns his Mr. mother costar Teri Garr, who died on October 29 at the age of 79.

“(It) is a day I dreaded and knew would come,” Keaton, 73, wrote on Instagram about Garr, who revealed in 2002 that she had been diagnosed with multiple sclerosis.

“Forget about how amazing she was as an actress and comedian. She was a wonderful woman. Not just amazing to work with, but amazing to be around. AND go back and see her comedic work – Man, was she amazing! !”

The pair starred as a couple in the classic 1983 comedy about Jack Butler, a married Michigan father who struggles with household chores when he’s laid off from his job and his wife Caroline (Garr) goes back to work. The film, which featured Keaton in his first leading role, also starred the late Martin Mull and Christopher Lloyd.

Talking to 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 want to talk about is the fabulous, and I mean fabulous legend, Teri Garr, how amazing she is and how sweet she is and how much fun we had on this movie,” said he.

“Regardless of this movie, if you watch… Just go watch Young Frankensteinman. And she’s still just so amazing,” he added.

Keaton said he knew the script, written by John Hughes, would make a great comedy.

“I remember reading the script. And I remember laughing out loud three or four times,” he said. “And to most people it seems like, ‘Well, it’s not much.’ But ask somebody. Because the other people you’re smiling at, or you’re smiling, are reading and thinking a little bit about it or imagining it. But if something gets make you laugh out loud, it’s encouraging to say the least.”

Keaton was right. Thanks to the chemistry and banter between the two leads, the film 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.

Before Mr. motherGarr made a name for himself in comedy, starring in hits such as the 1974s Young Frankenstein and the 1982s Tootsiefor which she earned an Academy Award nomination for Best Supporting Actress.

Garr died Tuesday “surrounded by family and friends,” publicist Heidi Schaeffer told PEOPLE.