Diane Keaton’s longtime friend is recalling her last moments with the late star.

In an emotional interview with PEOPLE, Grammy and Oscar-winning songwriter Carole Bayer Sager recounts her final visit with the Oscar winner, who died at age 79 in California on Saturday, Oct. 11, and recalls being surprised by her appearance.

“I saw her two or three weeks ago, and she was very thin,” Sager says. “She had lost so much weight.”

Sager, who co-wrote Keaton’s only solo single, “First Christmas,” explains that she’d seen her friend less this year because Keaton spent months in Palm Springs after the wildfires in California in January.

“She had to go to Palm Springs because her house had been damaged inside, and they had to clean everything,” says Sager. “She was down there for a while, and when she came back, I was kind of stunned by how much weight she’d lost.”

Still, “she was a magic light for everyone,” Sager adds. “I just loved her. She was so special, she just lit up a room with her energy. She was happy and upbeat and taking photographs of everything she saw. She was completely creative; she never stopped creating.”

That creativity included working together on “First Christmas,” which was released in November 2024, alongside co-writer and producer Jonas Myrin.

“She so loved recording this song,” Sager recalls. “She was almost childlike about it.”

Sager adds, “She was so authentic when she sang it, I mean, she just sang it like she was singing it, and she was sort of acting it, you know, because she is a great actress. And then she’d start to cry when she was singing it. But she did such a beautiful job.”

Sager says she also always admired Keaton’s style. Recalling how the late actress never wasted an opportunity to show off a cool outfit at their get-togethers, she says of Keaton, “She went to the movies always dressed like she was about to shoot another scene for Annie Hall.”

“She’d wear her hats and her jackets and her baggy pants, and her belts,” continues Sager. “She was a fashion icon of her own making.”

“She was hilarious, a complete original, and completely without guile, or any of the competitiveness one would have expected from such a star,” Midler wrote. “What you saw was who she was…oh, la, lala!”

Another friend shared similar sentiments with PEOPLE about Keaton’s: “She was funny right up until the end,” the pal said. “She lived exactly how she wanted to, which was on her own terms, surrounded by the people and things she really loved.”

“In these last few years, she kept a close circle and she liked it that way,” the friend, a film executive,” continued. “She was funny right up until the end and she had this way of making even ordinary moments feel special. That was just who she was.”