Host John Salley tried to maintain control as the reunion imploded.
The hit reality series airs Monday nights on VH1.
Andy Cohen made the announcement Friday at BravoCon.
Brandy, Whoopi Goldberg, Paolo Montalban, Victor Garber, Bernadette Peters, Jason Alexander and Veanne Cox will take part.
The one-hour reunion special airs at 10:00 p.m. ET/PT on Aug. 11.
Team behind the show reunited at the Tribeca Film Festival.