In a sneak peek at the interview, set to air Sunday in the US, Jenner, 62, opens up about how her infidelity tore their relationship apart.
“I married Robert when I was 22 years old and I got pregnant on my honeymoon — I had the happiest life you could’ve dreamt about,” she recalls to host Harvey Levin. “But when you’re in something, sometimes people think the grass is always greener and that was like what I think I went through at some point.”
Asked about her “affair with a soccer player,” Jenner acknowledges that it’s true.
“I did, I did,” she says. “Which wasn’t — nothing I’m proud of. When I look back on it now, probably one of my biggest regrets in my life is that that marriage fell apart.”
Jenner and Kardashian were married from 1978-1991 and welcomed four children together: Kourtney, 39, Kim, 37, Khloé, 34, and Rob, 31. Jenner admits she was devastated when Kardashian filed for divorce.
“Because it made it real,” she says. “Like, you think you’re going to come through this period — that was really hard for me.”
It also presented financial challenges as Kardashian — a high-powered businessman and attorney — cut off her credit cards.
“I didn’t have anything,” she recalls. “I went to the market one day and my credit card didn’t work. I had a market credit card and I’m like, ‘I can’t even buy a tomato.’ “
Jenner previously opened up about cheating on Kardashian in her 2011 memoir, Kris Jenner…And All Things Kardashian. In 1989, she had an affair with a professional soccer player a decade her junior, which prompted the divorce.
In 2016, Jenner told Harper’s Bazaar that the divorce was one of her only regrets, saying, “I had a wonderful, beautiful life with Robert. He was just an amazing man.”
Daughter Khloé has also spoken out about the divorce, vowing never to be unfaithful herself because of what she witnessed between her parents.
“I saw how it destroyed my dad,” she said on a Kocktails with Khloé episode in 2016. “I saw what it it did to my dad so I don’t want to do that. I also saw the regret from my mum.”
This article originally appeared on PEOPLE