Wow, it sounds like you really want her back. You just have to show her this. Make a massive gesture, or a few massive gestures. She might resist at first, as you've obviously hurt her, but at least you know this and you're sorry. It might sound a bit stalkerish but how about showing up unannounced with a thoughtful present, something that references the time you've spent together, along with a heartfelt apology and confession of your true feelings!