Erin Moran’s “Happy Days” co-star Anson Williams shares devastating details about her secret cancer battle

Actress Marion Ross, third from left, one of the stars of the television show "Happy Days," poses with the show's producer Garry Marshall, left, and and co-stars Tom Bosley, Erin Moran, Henry Winkler and Anson Williams, left to right, after receiving a star on the Hollywood Walk of Fame in the Hollywood section of Los Angeles, Calif., July 12, 2001. (AP Photo/E.J. Flynn)

Erin Moran’s sudden death continues to get sadder and sadder.

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Moran’s “Happy Days” co-star, Anson Williams is the latest to open up about the actress and her battle with Stage 4 cancer.

“It’s hard to wrap your arms around it,” Williams told PEOPLE. “She was having treatment for throat cancer, so I was contacting her husband and her, and she seemed to be fighting it, really doing well. I was just shocked when I got the call she had passed. I had no idea it was that bad.”

Williams was reportedly one of the few people that knew she was receiving chemo and radiation treatments.

“She kept very quiet,” he said. “We all kept quiet too, out of respect for Erin. She couldn’t speak, but her texts were very [positive].”

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Williams remembered Moran as she was portrayed in the “Happy Days” series: happy, upbeat and smiling.

“Erin always brought light into a room,” he said. “She always gave before she took, she was a very kind, generous person, but going through her own demons. Most of the time when I’d see Erin it would be an event, something kind of special. It would be a couple of days and quality time.”

Moran was found unresponsive in her mother-in-law’s home on Saturday. She was later pronounced dead at the age of 56.

Her TV brother, Ron Howard, also opened up about their relationship and what he knew about her illness.

“It’s been a rough time,” he told the hosts of “The Talk.” “Bill Paxton, we lost a while back, a very good friend. My stepmother Judy passed away a couple of months ago, so the Erin event really did hit hard and shock. I had no idea she was ill whatsoever.”

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