Catherine Zeta-Jones says the secret behind her lasting union with Michael Douglas is having “a very open relationship.”

The 49-year-old Welsh actress told “Today” hosts Savannah Guthrie and Hoda Kotb Tuesday that being completely candid with her husband of nearly 20 years has made their relationship work despite maintaining Hollywood careers and being faced with public scandal.

“First of all, I’m so happy that we’ve made it 20 years together,” said Zeta-Jones. “It’s been great, but I think it’s just unfathomable to me that you would be with one person for 18 years and things are not rosy every day. They’re just not.

“… Both Michael and I have a very open relationship. When you have kids that didn’t ask to be born into a world where it’s scrutinized or looked into… You’ve got to be open and honest and share things that probably people at the drugstore wouldn’t share over the counter.”

And when it comes to Douglas, 74, Zeta-Jones insisted that he’s “doing just fine.”

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When Guthrie, 46, brought up the sexual allegation claims that targeted Douglas earlier this year, Zeta-Jones revealed that the family “shares everything around the table.”

“I’m a big European kind of family girl,” she said. “And so everything is shared around the table… And so, I think you clear the air. And everyone knows what’s going on. It’s no big surprises.”

Zeta-Jones’ declaration comes just days after she told The Times of London she was heartbroken when Douglas was accused of sexual misconduct.

“My children and I were profoundly devastated by those allegations,” admitted Zeta-Jones on Sunday. “And I was torn about where my absolute morals lie. This woman came out of nowhere and accused my husband. I had a very big conversation with him, with the kids in the room, and said, ‘Do you understand if more comes out…’”

An employee who used to work for Michael Douglas claimed the actor sexually harassed her in the 1980s. (AP)

In January of this year, journalist Susan Braudy claimed that Douglas, 74, masturbated in front of her during a meeting in the late 1980s when she worked for his production company. In response, Douglas told Deadline that the allegation was “a complete lie, fabrication, no truth to it whatsoever.”

“My kids are really upset, [and they have] to go to school worrying this is going to be in some article about me, being a sexual harasser,” the actor said at the time. “They’re scared and very uncomfortable…. I’m bewildered why, after 32 years, this is coming out, now.”

Zeta-Jones and Douglas have been married since 2000. They share an 18-year-old son named Dylan and a 15-year-old daughter named Carys. Douglas is also the father of 39-year-old son Cameron from his previous marriage to Diandra Luker. That union lasted from 1977 until 2000.

Zeta-Jones, a public supporter of the #MeToo movement, added Douglas reassured her and their children that “there is no story here and that time will tell.”

“There was nothing to back it up at all,” she said. “For any accusation that comes out that isn’t backed up, that knocks the movement back 20 years.”

Michael Douglas and Catherine Zeta-Jones (AP)

Still, Zeta-Jones added, “it was a really hard position for me and, in the height of it all, it was nasty.” And while there may be ups and downs in their marriage that is scrutinized by the media, she’s not the type of person “to throw the towel in very quickly or anything.”

Braudy previously told The Hollywood Reporter that the “Fatal Attraction” star sexually harassed her on multiple occasions. Braudy claimed the Academy Award-winner, who was at the prime of his career, commented on her appearance and openly spoke about his affairs with actress Kathleen Turner and a European heiress. She alleged Douglas said inappropriate things to her.

Douglas responded to the allegations by also telling The Hollywood Reporter Braudy’s claims were “an unfortunate and complete fabrication.”

However, Douglas “acknowledged inappropriate discussions but refuted her claim of a hostile workplace."

“Coarse language or overheard private conversations with my friends that may have troubled her are a far cry from harassment," Douglas said. "Suggesting so does a true disservice to those who have actually endured sexual harassment and intimidation."

Actors Michael Douglas, left, and Catherine Zeta-Jones arrives at the Oscars at the Dolby Theatre on Sunday Feb. 24, 2013, in Los Angeles. (AP)

Braudy told The Hollywood Reporter she was not “surprised Douglas came out swinging against her.”

"I believe this is part of the problem, as is his pretext of victimization," Braudy said. "These are some reasons why so many women don't come forward with their stories — Lord knows it’s taken 30 years and a movement for me to gather my courage."

Fox News’ Kathleen Joyce and the Associated Press contributed to this report.