I'm so sorry that you are going through the pain of a breakup. It sounds like your ex-girlfriend really means that she isn't "in love" with you, and in that case there is nothing you can do to "get her back." One either has those feelings for another person or they don't. It doesn't necessarily have anything to do with your having treated her shabbily.
If you want to contact her in another month or two and talk, that is fine, but it doesn't sound like she is interested in any further relationship other than friendship. The mature thing to do is to move on, since she has.
Please hit "reply" if you have further questions about this.