In her confessional interview, Kim Kardashian shares her wariness about Khloe speaking to Lamar. "I don't know why Khloe and Lamar are talking, but he hurt her so badly," the reality TV star explains.
"As a big sister I'm just really protective, and for her just to be flirting with him on the phone makes me sick to my stomach," Kim continues.
Khloe and Odom split in December 2013, after four years of marriage.
Khloe, 31, filed for the divorce amid rumors of Odom's alleged drug use and infidelity, citing "irreconcilable differences."
Kim, 34, confronts Khloe about her interaction with Lamar after she hangs up the phone.
"I just can't take it," Kim tells Khloe in the clip. "The fact that when he decides to come around and be friendly, you're like, flirting with him."
"I'm flirting with him how?" Khloe retorts. "By answering the phone and saying hello?"
Kim replies that she thinks Khloe is "way more attentive" to Odom than to her most recent ex-boyfriend, French Montana.
"Why would French and Lamar even be in the same category," Khloe responds.
The full "Keeping Up With the Kardashians" episode will air this Sunday, Oct. 4 at 8 p.m. ET on E!.