Danny Bonaduce Remembers 'Partridge Family' Costar David Cassidy: He Was 'a God'

In the early 1970s, David Cassidy was a teen heartthrob who seemed to have everything going for him, from performances in arenas to thousands of screaming fans to his face regularly landing on the cover of magazines.

“From 1970 to 1974, it was like being in the company of a god,” his Partridge Familycostar, Danny Bonaduce, tells PEOPLE. “Normal things didn’t happen for David Cassidy. He wasn’t just like an older brother; he was my idol, too.”

Bonaduce says that Cassidy had a hectic schedule. “He’d leave work [filming The Partridge Family] on Friday, then be in an 100,000-seat arena in Australia that weekend, wearing the wildest jumpsuit you ever saw,” Bonaduce says. “He’d sell the stadium out, bring the girls to hysteria, and then get back to work on time on Monday morning.”

“There was something otherworldly about being around David Cassidy,” Bonaduce continues. “He was a huge star.”

Bonaduce and Cassidy remained close until Cassidy died of organ failure on Nov. 21, 2017, at the age of 67. “I was completely shocked when he died,” says Bonaduce. “I thought he was doing better.”

As it turns out, Cassidy was hiding a secret: he wasn’t clean and sober.

While filming a documentary for A&E, he called the producers with a confession: “I have a liver disease,” Cassidy explained to A&E producer Saralena Weinfield in a recorded conversation. “There is no sign of me having dementia at this stage of my life. It was complete alcohol poisoning.”

As it turns out, Cassidy had been lying to everyone about his alcoholism. He had never stopped drinking and was blaming his behavior on dementia, which had plagued his late mother.

Cassidy then followed up with a shocking revelation. “The fact is that I lied about my drinking,” he said. “I did this to myself to cover up the sadness and the emptiness.”

• For more on David Cassidy’s final weeks, pick up this week’s issue of PEOPLE, on stands Friday

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Bonaduce was one of the people to whom Cassidy had lied.

“We were basically each other’s sober coaches,” Bonaduce says. “We talked about it; we worked on it. We’d call each other and ask, ‘How much time you got? How you doing? How’s the family? Who’s mad at you?’ That’s a really big one with addiction: Who’s mad at you? So from about five to six years ago to the end, we would check in on each other with a great deal of love and affection.”

Bonaduce, who fought his own addiction issues in the ’90s, says he understands a lot about Cassidy’s last days.

“Part of alcoholism is lying,” says Partridge costar Danny Bonaduce. “When you’re an addict, you know you can’t be honest with people. You say what you want them to hear. I can’t be mad at David for that, but it’s still a tragedy.”

David Cassidy: The Last Session airs June 11 at 9 p.m. on A&E.