The 81-year-old actress and comedian revealed to Splash News over the weekend that the 24-year-old star has threatened her with a lawsuit. Stewart initiated legal action after she discovered Rivers insults her in her new book, Diary of a Mad Diva.
"Many stars only do one thing well," the Fashion Police host writes in the memoir. "Of course, the best one-trick pony is Kristen Stewart, who got a whole career by being able to juggle a director's balls."
Stewart found herself at the center of controversy in July 2012 after she and her Snow White and the Huntsman director, Rupert Sanders, were found to be having an affair. The actress was dating Twilight co-star Robert Pattinson at the time, and Sanders was married to model Liberty Ross. Both relationships ended as a result.
"She obviously didn't read our disclaimer, which is that it's a comedy book," Rivers tells the celebrity news website. "I can't wait to get her into court because I want to get a puppet and I want her to show me on the puppet where she thinks I claimed she touched her director. So I am looking forward to it."
"I'm a comedian; I've been doing it for 50 years," she continues. "If people don't get it, then don't come and see me, and don't read the book. If you're going to take it seriously, you're a fool."
Rivers says "her lawyer contacted my lawyer," but a source tells TMZ Stewart's attorney may have backed down. Diary of a Mad Diva will be released July 1 in the U.S.