The television personality dropped the bombshell during the fourth season premiere of reality show The Kardashians.
She had an argument with Kim from the previous season, as the latter partnered with fashion company Dolce & Gabbana, Kourtney's wedding designer, just less than a year after Kourtney's wedding to musician Travis Barker in May 2022.
In the fourth season premiere, the Kardashians are off to a vacation in Cabo San Lucas in Mexico, but Kourtney didn't join.
She said she had a heated phone call with Kim three days before the trip.
During the call, Kim said she was going back to Milan for a Dolce & Gabbana event. She then invited Kourtney, who politely declined and mentioned how it "isn't cool" how the collaboration happened.
The sisters then had a word war, as they talked about their family, attention, and happiness.
"I was like, wait nothing happened at the wedding, it wasn't even a conversation at the wedding," Kim said.
Kourtney replied, "I think it was what you saw at the wedding because nobody had any interest before that. You saw this thing that was mine and wasn’t yours, and you wanted it."
She also claimed that Kim didn't seem happy for her when she got married. "You cannot stand someone else being the center of attention. You came to my wedding, you couldn’t be happy, you complained from the second you got there till the second you left. You couldn’t be happy for me, you couldn’t be happy that I was the center of attention."
Kim asked if Kourtney was happy, to which she responded that she's happy when she's not on the phone with Kim.
"I have a happy life," Kourtney said, "and that happiness comes when I get the f—k away from you guys. Specifically you."
Kim then mentioned that Kourtney's kids have come to her about their problems and how she is, which Kourtney took as Kim "using any weapon she could find" to hurt her.
"Is that helpful? You're adding it into a fight to have a side. It's you and my friends and my kids and everyone against me. You're just a f—king witch and I f—king hate you."
After the heated exchange, they agreed to do a joint confessional.
The Kardashians is now streaming on Hulu.