“I couldn’t be more elated for her,” the reality star, 73, tells PEOPLE. “I have no doubt she’s going to be a great mom.”

Chastain, 39, starred alongside Rosbach for six seasonsbefore departing the showin February 2020. This is her first child, whomshe has said she will be raising “solo.”

“She’s taken on a big challenge, but she’s more than up to it,” Rosbach says. “And I don’t think I’ve ever seen her this happy.”

PEOPLE reported news of Chastain’s pregnancy exclusivelyon Dec. 13, with Chastain — who is due on May 8, 2023 — saying that she’d long hoped to have a child of her own one day. “I am absolutely thrilled to become a mother,” theTraitorsstar shared. “It’s something I’ve always hoped for so this is truly a dream come true!”

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Charles Sykes/Bravo/NBCU Photo Bank via Getty

WATCH WHAT HAPPENS LIVE WITH ANDY COHEN – Episode 17002 – Pictured: (l-r) Captain Lee Rosbach, Kate Chastain – (Photo by: Charles Sykes/Bravo/NBCU Photo Bank via Getty Images)

So is Rosbach up for the task? “Well, I don’t do diapers,” he tells PEOPLE. “I’ll do a lot of things, but diapers aren’t one of them.”

Still, he and his wife Mary Anne plan on being there for Chastain whenever she needs, he says. “Somebody on Twitter the other day said, ‘Oh, grandpa, Captain Grandpa,’ which I thought was a sweet thing,” he adds.

Dimitrios Kambouris/Getty

NEW YORK, NEW YORK - NOVEMBER 15: Kate Chastain and Lee Rosbach attend the opening night of 2019 BravoCon at Hammerstein Ballroom on November 15, 2019 in New York City. (Photo by Dimitrios Kambouris/Getty Images)

Rosbach’s exit fromBelow Deckplayed out on Monday’s episode of the Bravo series after he informed his crew that persistent health issues meant he’d need to bow out ofseason 10early.

“That’s something I’ve never done in my life,” he says, looking back on his announcement. “I’ve never quit. I’ve never had to say I quit. And it was really, really hard to admit, especially to myself, that there’s something out there that kicked my ass.”

He will be back, later in the season, to finish what he started, PEOPLE revealed after the episode on Monday. But whether or not he returns for season 11 — or if there is a season 11 — remains to be seen.

Asked if he’d return, Rosbach replies, “Absolutely.”

source: people.com