Barton was just a teenager when she was cast as Marissa Cooper on "The O.C." in 2003, a time when Perez's blog was at its height. In the series premiere, she said Hilton "loved coming after me" at the time, calling him a "total bully" and someone who was "awful to me and lots of women."
Tonight, she was able to tell him how his posts really made her feel right to his face.
The entire cast attended a party to celebrate Stephanie Pratt's return to Los Angeles, with Spencer Pratt inviting Perez so he could have a chance to apologize to Barton in person. He did ... but she didn't accept it.
"Perez Hilton was a pseudo-celebrity blogger. He was the face of a certain brand of hate," Barton said in a confessional. "I really felt like I was a target for him. I don't know how to describe it, it's just like when you see your bully in the school hallway. That adrenaline gets going, it's a mixture of fear and anger and all of those things."
Speaking to Whitney Port at the party, she added, "Ultimately, it affected my career, it affected my life. He's just a scumbag. At the end of the day, he's a scumbag." She then went right up to Hilton to talk about the "apology" he wanted to give her.
"The thing with that is, this bullying that you did for so long to so many young girls, I find it hard to let go. I really do," she said to him. "It's not just about the body shaming or outing people who are gay before they're out of the closet, all of that stuff, I just can't really accept the apology entirely on behalf of how I truly feel. I think really where I think the divide between us is I don't sit well with people who purposefully harm other people."
Perez acknowledged what he was doing at the time was "wrong," before expressing his regrets.
"If I could go back in time -- and I say this on my kid's life, I swear -- if I could go back in time and do things differently I would," he said. But Barton was still livid. "Would you, would you really?" she asked, "You would go back in time and change all of those peoples careers you messed with, all of the people you outed?"
Her anger after he had just "swore on my kids' life" offended Perez, who was shocked Mischa was still "shitting on" him by questioning his apology. With that, he stormed off.
"He's just being a total dick," Mischa exclaimed.
As Mischa spoke with Audrina Patridge and Whitney on a hike the following morning about the incident, Patridge gave her props for standing up to the blogger.
"You stuck up for a lot of people to him, you confronted him about everything," she said. Port also called it "cowardly" that he ran off from the argument. When Mischa noted that she didn't feel that the conversation "was going to end in hugging it out," Port added, "He doesn't deserve that."
At the end of the episode, Barton said the confrontation was "definitely cathartic" and gave her a "renewed sense of confidence" dealing with others going forward. "I feel like this is my chance to not be the vulnerable, meek Mischa who gets pushed around by people," she added.