Jermaine Jackson Claims Rape Accuser Ruined Son Jafaar's 'Michael' Biopic Promo

Jermaine Jackson feared claims that he raped a woman would tarnish not only his reputation, but also his son Jafaar Jackson's big break in the "Michael" biopic ... TMZ has learned.

In new legal docs, obtained by TMZ, Jermaine said he was unaware of Rita Butler Barrett’s lawsuit against him … or the $6.5 million default judgment she was awarded in May ... until he got blindsided during the press tour for the biopic.

He says the coverage of the default judgment ruined "what should have been a proud and important professional moment for my son and our family." He says he was "shocked and deeply concerned about the effect of those reports on my reputation and on the promotion of my son's motion picture.”

Rita claimed Jermaine sexually assaulted her in 1988 after he showed up at her home uninvited. He denies the claims.

As TMZ first reported, Jermaine is making moves to have the massive default judgment thrown out, claiming he had no idea about the suit and wants an opportunity to defend himself.