In an exclusive clip obtained by E! News, the reality star revealed during an exercise on Marriage Bootcamp: Reality Stars that she is "angriest" at LC, her "former best friend," who she claims, "tried to just ruin my life with her lies."
On the show, Montag was told she can either choose the path of forgive or forget (literally, there were two walkways labeled "forgive" and "forget").
"Well, she so famously said she wants to 'forgive and forget you' and I just wanna forgive her," Heidi decided, and began walking the blue-lit maze. "I definitely feel the weight of the emotional baggage that I carried from this person and I'm sick of it," she told the cameras.
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Once she finished her walk and exited on the other side, she was greeted with a female who would now pretend to be Lauren, so that Heidi can say whatever it is that's been on her mind all of these years.
"I am so mad at you for feeling like, because you put me on TV, I was indentured to you for everything. I am so mad at you, how awful you treated me," Montag began to say, but was interrupted by responses like, "I made you!"
The emotions got high and the yelling started to go full throttle. Then Montag shouted, "You had your sex tape and you blamed it all on me!"
While it's no secret that these two never chose to rekindle their friendship, the intensity of the bad blood between them may be a little surprising. A little over a year ago, Montag revealed that she had spoken to Lauren a few times since The Hills wrapped, and seemed to express that things were civil between them.
"I do really appreciate everything that she's done for me and I'll always have such great memories about her and, you know, without her I wouldn't have any of the world that I have today or my husband," Montag said. "It's unfortunate things happened the way that it did, but we're both different people now, older and more mature."