Kardashian matriarch Kris Jenner opened up about cheating on her then-husband and father of her four kids Robert Kardashian Sr. on Thursday's episode of The Kardashians, which she called her “life's biggest regret.”

Jenner was speaking with her daughter, Khloé Kardashian about why she had an affair with the soccer player-turned-animator Todd Waterman in 1989, which broke up her marriage and lay the groundwork for more Kardashians and their eventual reality television empire.

“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,” Jenner explained.

The topic came up amidst a discussion about Khloé's ex, Tristan Thompson. “What was your mindset when you cheated?” Khloé asked her mom. “When you did that with my dad, and you had four kids and you had a family? Yes, I know you were really young….”

Ouch. That had to sting a bit, but Kris calmly responded, explaining that “being really young and dumb is something that plays into it because you don’t really understand the consequences of your actions.”

Khloé prodded further, asking Jenner, “But what was my dad not doing that made you want to look elsewhere?”

It could have gotten pretty awkward there, but this is when Kris chimed in about thinking the grass could be greener, while admitting “I made a huge mistake. That’s my life’s biggest regret.”

Jenner elaborated further in a confessional interview segment. She spoke of her desire for Khloé to really think it over before completely cutting ties with Tristan, the father of her daughter, True, 5, and son Tatum, 13 months.

“When I got divorced, Robert and I became best friends. We talked on phone all day long, helped each other through things all the time, and I did have regrets,” said Jenner. “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.”

Besides, as Los Angeles residents, these days Kris Jenner and the rest of the Kardashians shouldn't be worried about whose grass is greener anyway, they should be more concerned about whose yard is the most drought tolerant.