Kris Jenner is speaking up about a "mistake" she committed that continues to bother her. On this week's episode of The Kardashians, Kim Kardashian opened up to her daughter Khloé Kardashian about the time she cheated on her late ex-husband and Khloé's father, Robert Kardashian Sr, whom she married from 1978 until 1991. Jenner and Waterman subsequently divorced following Jenner's 1989 romance with soccer player and animator Todd Waterman, which she describes as her "life's biggest regret."

The mother-daughter pair were discussing Khloé's relationship with Tristan Thompson, her ex-husband and the father of her two children, True and Tatum. He famously cheated on Khloé several times. Khloé questioned Kris, "What was your mindset when you cheated?" to get into the head of a cheater. When you did it with my father, you had four children and a household. Yes, I realise you were rather young..." 

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Kris reacted by pointing out that "being young and dumb is something that plays into it because you don't understand the consequences of your actions."

"But what was my dad not doing that made you want to look elsewhere?" Khloé persisted.

"I don't know, because he was such a great husband and such a great dad, and I think that I fell into a situation where I thought that the grass was greener somewhere else, and I made a huge mistake," Jenner admitted. "That’s my life’s biggest regret."

"When I got divorced, Robert and I became best friends. We talked on the phone all day long, helped each other through things all the time, and I did have regrets," Kris said during a confessional, adding that she hopes Khloé will rethink fully severing her relationship with Thompson. "I thought, Wow, what I was thinking? So, I want Khloé to be really careful when she makes these decisions and she has to let somebody go."

The tape returned to Jenner and Kardashian's talk, and Jenner stated that, while she regrets her mistake, she is convinced that everything has worked out as it should.

"I'm not proud of how I acted at the time, but you know what? "Everything occurs for a reason," she explained. "I do live my life by thinking God has a plan, and without that whole thing happening, there never would've been Kendall and Kylie [Jenner]."