Cassie, an R&B singer who was once signed to Sean Combs’ label, filed a lawsuit against the producer and music mogul, who has been one of the most well-known names in hip-hop for decades, in federal court on Thursday. Cassie accused Mr. Combs of sexual assault and of abusing his body repeatedly over a period of around ten years.

In the suit, filed in Federal District Court in Manhattan, Cassie, whose real name is Casandra Ventura — and who had long been Mr. Combs’s romantic partner — says that not long after she met him in 2005, when she was 19, he began a pattern of control and abuse that included plying her with drugs, beating her and forcing her to have sex with a succession of male prostitutes while he filmed the encounters. In 2018, the suit says, near the end of their relationship, Mr. Combs forced his way into her home and raped her.

I am finally ready to tell my story, and to speak up on behalf of myself and for the benefit of other women who face violence and abuse in their relationships,” Ms. Ventura said in a statement, following years of quiet and gloom.

In response, a lawyer for Mr. Combs, Ben Brafman, said: “Mr. Combs vehemently denies these offensive and outrageous allegations. For the past six months, Mr. Combs has been subjected to Ms. Ventura’s persistent demand of $30 million, under the threat of writing a damaging book about their relationship, which was unequivocally rejected as blatant blackmail. Despite withdrawing her initial threat, Ms. Ventura has now resorted to filing a lawsuit riddled with baseless and outrageous lies, aiming to tarnish Mr. Combs’s reputation and seeking a payday.