Teen Mom OG Reunion Sneak Peek: Dr. Drew Questions Matt About Gary's Bombshell Allegations

Plus, see Amber's fiancé and her ex take the stage together in the upcoming special.

Gary approaching Amber with papers claiming that her fiancé Matt has seven children was arguably one of the most talked-about moments from this Teen Mom OG season -- and during Part 2 of the upcoming reunion special, host Dr. Drew honed in on this controversial subject with the New England native and asked the MTV cast member to tell "his side of the story."

"This should be fun," Matt states with a slight smile in the sneak peek above from the upcoming episode.

But the conversation quickly shifted back to Leah's father -- and Matt's take on why Amber's ex behaved this way in front of the crew.

"His motivation for doing what he did was not what he said. His motivation was different," Matt says. "If he had that motivation, he would have called her and said 'Hey, what's going on with this?' Instead, he purposely waited for the cameras."

While the Indiana native sits quietly, Dr. Drew can't help but ask why Matt wasn't honest with his partner. Hear Matt's explanation -- plus, see Matt and Gary discuss their issues in the video below. And be sure to catch Part 2 of the Teen Mom OG reunion on Monday at 10/9c.