Kaley Cuoco Honors Late Costar John Ritter at An Evening from the Heart Gala By Sharing her Favorite Memory (Exclusive)

Kaley Cuoco on May 9; John Ritter in 2002. Photo:

Rodin Eckenroth/Getty; Jean-Paul Aussenard/WireImage

Kaley Cuoco is honoring her late TV dad!

The actress, 38, dressed to the nines at An Evening from the Heart, a gala presented by The John Ritter Foundation for Aortic Health on Thursday, May 9 at Sunset Room Hollywood in Los Angeles.

The event celebrated the life and legacy of Cuoco's 8 Simple Rules costar John Ritter, who died in 2003 at the age of 54 of a "misdiagnosed acute aortic dissection," according to the foundation's website.

"He touched a lot of lives," Cuoco tells PEOPLE in an exclusive interview at the event. Cuoco said she became very close to Ritter's family, who has "worked very hard" for the past two decades to bring awareness to aortic dissection.

"I will do anything for his wife and his kids," Cuoco says. "And I'm so really very proud to be here and honoring him."

Stars like Cheri Oteri and Holly Robinson Peete also attended the event to raise money for the organization, founded by John's wife Amy Yasbeck Ritter in 2003 to "spread awareness of aortic health and prevent unnecessary suffering through genetic research, widespread education, and radical advocacy," according to the website.

Amy attended the gala along with John's son, Tyler Ritter — one of the late actor's four children.

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Cuoco and Ritter starred as father and daughter Paul and Bridget Hennessy on 8 Simple Rules for two seasons from 2002 and 2003 before his unexpected death. The show — which also starred Katey Sagal as matriarch Cate Hennessy, Amy Davidson as Bridget's sister Kerry and Martin Spanjers as her brother Rory — lasted for one more season after John's death.

On Thursday, Cuoco recalled how Ritter would do anything for a laugh.

"He was so funny, and he loved his fans," Cuoco tells PEOPLE. "He was so good. I remember when we were shooting Eight Simple Rules, [he] used to tell me that he would mess up in front of the audience on purpose to make them laugh."

"And I was like, 'No way!'" she recalled. "And then I would watch him mess up over and over when I knew he knew the scenes, and I took that with me for a long time."

"He didn't take himself seriously. And I feel like we need to get back to what that is not taking ourselves so seriously," Cuoco added.

Cuoco has attended the event in the past, including in 2023 when she reunited with Sagal, 70, Spanjers, 37 and Davidson, 44, to honor John and spread awareness. The Big Bang Theory gave the opening remarks for the evening in 2003, thanking her former costars for attending.

"This is really awesome. I think John is laughing his a– off right now. He cannot believe we're here," she said in her speech.

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The Flight Attendant star appeared to have a close relationship with her sitcom dad and continually writes tributes to him on the anniversary of his death.

"Thank you for continuing to make me laugh every single day 💜💜," she wrote in an Instagram tribute in 2020.