Farrah Abraham says a 'Teen Mom' honcho ridiculed her for her adult film work, and she's not gonna take it laying down ... she's taking the whole company to court.

Farrah says she met with Morgan J. Freeman (no relation), an executive producer on "Teen Mom OG," at her home in Texas last October. In a lawsuit, she says Freeman harassed, humiliated and degraded her doing porn.

The 'Backdoor Teen Mom' star says Freeman went on to threaten her future career at MTV, and she "feared for her life" because he was hostile toward her. According to docs, obtained by TMZ, shortly after the meeting MTV fired Farrah from the remainder of the 'OG' season, and also pulled the plug on negotiations for a long-term deal.

MTV aired portions of Farrah and Freeman meeting in a preview for the current season -- it was clearly tense, but there was no mention of her porn career in the clip that aired.

MTV

Farrah's suing Freeman, Viacom -- MTV's parent company -- and a few smaller production companies for at least $5 million.