When the latest season of Teen Mom OG ended, the last glimpse of Farrah featured the young mother feuding with MTV producer Larry. And during Part 1 of the upcoming reunion special (airing on Monday), host Dr. Drew asked the 24-year-old about the fight. But shortly after Farrah admitted that relations were "fine" with Larry, the conversation quickly took a difficult turn -- specifically, the addiction specialist bringing up a "horrific" incident from Farrah's childhood.

"There is something called traumatic re-enactment that humans do," Dr. Drew explains in the sneak peek above. "One of the crazy things about humans is that when something bad happens to us, particularly in childhood, we'll reenact it over and over again in our adult life."

"Yeah," Farrah responds softly.

"You've had some things happen to you that you would not do today," he continues.

This statement hits a painful chord with Farrah -- and she becomes visibly emotional and upset. Watch the entire exchange above -- plus, hear her father Michael open up about his daughter's adult video in the clip below. And be sure to catch Part 1 of the Teen Mom OG reunion on Monday at 10/9c.