Well think, that's her problem not yours. She needs to realize that she got dumped and needs to get over it. But you don't have to put yourself into HER situation. She needs to fix her own issues, not have people fix them for her. So live your life, with no regrets and let her live her life, the way she deals with it. Past is History:P
First thing you could probably do to make her like you a little more is use proper grammar. Secondly just give her some time and avoid say anything negative about her to anyone they always seem to hear that stuff. It's like a sixth sense. Lastly just talk to her casually and friendly when the opportunity presents itself.