They won't be able to put him away for rape unless they find evidence that says he did it. No evidence, no conviction. There has to be evidence to convict your brother.
{with the badass guys thing} I do :D My friend Joey is all badass and scary, but he's really like a scared puppy who I wanna cuddle all the time He's really nice and kind of protective of me, which is something I don't really mind. And ever since I started hanging out with him the other asses at my school, specifically the really tall and some of the scary/meaner kids haven't bothered me at all. Ain't that nice? We met from playing football :D
Wait, what is your brother getting tried for? Is it rape? If not then he can sue her for slander. She actually can't make a claim he raped her and spread around that he did if he didn't. That will tarnish his reputation and therefore he has a defamation case against her. Let her know that next time she starts saying it around. If it is true though then she has every right to press charges. I'm not sure someone who's been raped would spread it around so freely like that and not take any action. She sounds fishy.