The battle between Rihanna and Chris Brown's new girlfriend Karrueche Tran is hotting up it seems. After having a pop at each other on Twitter recently, RiRi has now decided to try and get Chris to dump her. She's told her violent ex-boyfriend to break-up with the half-Vietnamese model within the next two weeks or else she'll never speak to him again. Sounds mature doesn't it? And of course if he does split with her, then Rihanna has promised ...