Rihanna is having a Twitter spat with who Mon-27-Aug-12 16:55 Share this By MeganRihanna has taken aim at Joan Rivers after the outspoken comic mocked the pop star over her candid interview with Oprah.The Umbrella hitmaker broke down in tears during a chat with Winfrey for her OWN network earlier this month when she admitted she still loves her ex-boyfriend Chris Brown, who was charged with assault and placed on probation after he beat her in 2009.The comment irked Rivers, who took to Twitter.com to call the star out on her confession, writing, "Rihanna confessed to Oprah Winfrey that she still loves Chris Brown. Idiot! Now it's MY turn to slap her."Rihanna quickly retaliated, replying, "Joan Rivers wow u really do get slow when you're old huh?", before adding, "Slap on some diapers."River then tried to make amends by inviting her on her show Fashion Police, writing, "Honey, Rihanna, everyone knows: If he hit you once, he'll hit you again. Read the statistics. PS - Love to have you on Fashion Police!" You May Also Like Sophie & Sharyn get their bums out like Rihanna Rihanna's new vid 'We Found Love' Real names of celebrities that will surprise you Become a fan of The Edge on Facebook and on Twitter .