Joan Rivers has insulted Kristen Stewart regarding the actress’s infamous affair with Rupert Sanders back in 2012 with her new novel, Diary of a Mad Diva.

The affair between Stewart and Sanders, the director of her film Snow White and the Huntsman, was made public by US Magazine with scandalous photos in July 2012.

Rivers, 81, is no stranger to slamming celebrities with harsh criticism that serves to ultimately strengthen her controversial career. Kristen Stewart has become one of the many unlucky celebrities to get struck with such biting insults. According to the International Business Times, Rivers writes, “Many stars only do one thing well. Of course, the best one-trick pony is Kristen Stewart, who got a whole career by being able to juggle directors' b****.”

Stewart is reportedly not the only celebrity under fire in Diary of a Mad Diva, although she is notorious for her reluctance to enter the spotlight. Has Joan Rivers finally gone too far?

Image courtesy of INFphoto.com