The 25-year-old and 26-year-old co-stars got into a physical altercation while filming the Season 6 reunion special Saturday, sources confirmed to E! News.
The Real Mr. Housewife blog had reported that Portwood and her fiancé, Matt Baier, confronted Abraham and her dad, Michael Abraham, at the reunion. Insiders said Portwood was angry about remarks Abraham and her boyfriend, Simon Saran, made about Baier.
"All was going well during the reunion. Farrah was taping her segment and Simon's comments about the other cast members came up," a source told the blog.
"When [host] Dr. Drew mentioned Simon had called Matt a pedophile, it seemed like he was heading in the direction of an apology, claiming it was all in fun. However, Farrah piped in and said, 'Well, he does kind of look like a pedophile,'" the insider said.
"At that point things got out of hand. Amber stormed onstage and started yelling at Farrah. [Michael] got out of his seat and got in between Farrah and Amber and was yelling at Amber," the source claimed. "Then, Matt came onstage and got in between Amber and Michael."
The insider said Michael Abraham put his hand on Baier's throat and that Portwood threw a punch at Abraham. Portwood shared her side of the story in a series of tweets on Sunday.
"Matt went out there to get me not fight..her dad got in my face so Matt got in the middle and Michael choked him so Matt knocked him on his [expletive]. While Simon sat on the couch the whole time lol," she wrote.
Abraham and Portwood came to fame on the MTV series 16 & Pregnant before starring on Teen Mom. Teen Mom OG airs Mondays at 9 p.m. ET.