In a sneak peek from the dramatic installment, below, host Dr. Drew asks Farrah's on-again off-again boyfriend Simon about some recent Snapchats which featured the SoCal-based entrepreneur speaking negatively about his fellow MTV cast members (the addiction specialist asked Amber about the same social media updates during Part 1).
"These people make themselves vulnerable -- they give you ammo to just talk about them," Simon explains, while adding that he means "no disrespect" and that it "was all in fun."
Meanwhile, the 25-year-old defends her friend's actions -- but doesn't mince words when comparing him to her longtime cohorts.
But the ill feelings only intensify when Dr. Drew asks Simon about calling Amber's fiancé Matt a "pedophile." Hear how the former couple responds to the query in the video below, and don't miss the entire reunion -- unprecedented fight included -- on Monday at 9/8c.