Catherine Zeta-Jones Reveals What Kirk Douglas Really Thought of Joan Crawford

Feud airs Sundays (10 p.m. ET) on FX

A version of this story originally appeared on EW.com.

When Catherine Zeta-Jones was doing research for her part on Feud: Bette and Joan, she had an excellent resource she could call on for advice: her father-in-law Kirk Douglas.

The actress plays Olivia de Havilland in the Ryan Murphy anthology series which follows the relationship of movie stars Joan Crawford and Bette Davis (played by Susan Sarandon and Jessica Lange) as they made Whatever Happened to Baby Jane? — a film that is now regarded as a cult classic.

• Watch Cagle’s full Town Hall interview with the cast of Feud, streaming now on PEOPLE/Entertainment Weekly Network at PEOPLE.com/PEN, or download the app on mobile or connected devices. You can also listen to the full interview on EW Radio (SiriusXM ch. 105) all this week

As Zeta-Jones noted during a SiriusXM Town Hall discussion with PEOPLE and Entertainment Weekly Editorial Director Jess Cagle, her father-in-law is only six months younger than de Havilland, with both actors turned 100 within a short period of each other.

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“He went, ‘Aaah Olivia’ and said nothing else,” said Zeta-Jones, 47, of when she told Douglas about who she’d be playing on the show. “I said, ‘And it’s about Joan Crawford and Bette Davis.’ And he went ‘Joan Crawford? She was out of her effing mind.”

“And then about Bette Davis, he went ‘Aww, she was a broad. She told it as it was,” laughed Zeta-Jones. “It sums up in one cup of tea, exactly where these women were coming from.”

Feud airs Sundays (10 p.m. ET) on FX.