"[My sister has] cussed me out two or three times," Lauren told ET Thursday. "She's called me a dummy and a few other things."
The Survivor cast member's sister Sunny Rimmer has been heavily-involved with the game the whole season, even dragging her sister to the casting call that got her on the show.
When Lauren made it and Sunny didn't, the contestant promised to "share every minute that I could with her, and that I would do my best to get her to the family visit."
In Wednesday's dramatic tribal council, Mike Zahalsky threw away half of the idol given to him by Lauren as part of an alliance into the fire, making her vulnerable for what her former ally, Ben Driebergen, was about to do — take out an idol to save himself.
"I was really just lost for words," Rimmer explained. "I would have never guessed in a million years that Mike would have done that. And I've asked him, like, 'Why did you do that?' He's like, 'I don't know. I just wanted to. I always wanted to.'"
"When I gave it to him, I was trying to keep him close. I wanted him to feel like he was included, and I was trying to secure that vote, along with Ashley and Devon, and obviously he had better plans for it," she continued, saying it "never crossed my mind" to try to grab the idol from the fire. "But who's to say if Jeff would have even let me play it?... But it would have been worth a try if it had crossed my mind."
She did have an extra vote advantage in her pocket, but had told everyone she had left it back at camp and decided ultimately not to use it.
"Nobody knew that Ben had an idol. I was trying really hard not to use it until I had to... and I was almost trying to reassure Chrissy, like, 'Stop, we can pull this together,'" she said.
"I think I went too soon gunning for Ben. We had a lot of trust between us, but at the same time, I knew in my mind, Ben's not someone that I can sit beside in the 1, 2, 3 seat, and I'm assuming he thought the same," she said. "I think I would have been fine if it wasn't for Ben. I think I at least would have made it another night, because Devon, myself and Ashley, we were working really well together."
Survivor airs Wednesdays at 8 p.m. ET on CBS.