Kristin Cavallari Details 'Trust Issues' After Fallout with BFF Over Jay Cutler Rumors
The Worst Celebrity Feuds

"I've had people in the past take advantage of me for their own personal gain," says Cavallari.

Kristin Cavallari is giving fans more insight into her brutal falling out with former best friend Kelly Henderson.

After opening up about what ended their friendship in the Season 3 premiere of "Very Cavallari," the reality star confides in colorist Justin Anderson about the feud in a sneak peek from Thursday's new episode.

The beef began when some of the show's fans started speculating Kristin's husband, Jay Cutler, and her glam squad member were having an affair. Cavallari herself never believed any of the talk, but was not thrilled with how Henderson reacted to the gossip.

"She won’t return my text messages," Cavallari tells Anderson in the video. "I was in Mexico filming a TV show and she literally didn't say one thing to me. Kelly, normally, would be like, 'How's Mexico? I know you're there alone for the first two weeks.' She literally didn't say one thing to me except for one text message asking if I've spoken with producers for 'Very Cavallari.'"

"The whole time her whole thing has been, 'I don't care about the show, I only care about your friendship,'" Cavallari continued. "She drank the Kool-Aid, big time. I thought Kelly was the last person on the planet that this would ever happen with."

In a confessional, Kristin talked about being burned in the past and having those same feelings now. "I have trust issues, I do," she confessed. "I've had people in the past take advantage of me for their own personal gain. When I started to feel like Kelly was really using me, it triggered something within me."

When Anderson said Henderson told him she was "hurt" by the situation, Cavallari didn't understand why. "What is she hurt about?" she asked. "I asked her, 'Have I done anything to hurt you, to make you upset, to make you not want to be friends with me?' and she was like, 'No you haven't done anything.'"

"Why didn't she tell me she was hurt throughout this entire thing?" she wondered. "I don't know what she's hurt about or upset about, honestly."

Kristin also claimed Henderson has "never once" said she was sorry for how the situation escalated and was instead "very defensive about it" when Cavallari tried to bring it up. Justin said Kelly "rolled her eyes" about it all when they spoke and said "This is so dumb" -- but he was Team Kristin, saying, "you didn't take care of your best friend."

According to PEOPLE, the two still haven't spoken in real life since the fallout.

In the premiere, Cavallari expressed frustration over how Henderson handled the rumors. She explained how Henderson would constantly bring up the rumors online, adding "fuel to the fire," which made Cavallari believe it was in self-interest.

"Why do you want to post about that? To get more attention about it," she said. "If I was accused of having an affair with your husband, I wouldn't say his f--king name on social media. Like, come on."

"Instead of her just owning her side of it and being like, 'I'm sorry! Oh my god, that was never my intention' or whatever, she kept giving me push back and would get really defensive," Cavallari explained. "And then, she literally just stopped responding to me."

"Very Cavallari" airs Thursdays on E!