Simple answer: Forget about her.
You can waste all the time in the world wondering what you could've done different, wondering why she's acting this way, wondering if there's a way to save it, wondering if it's something intrinsically wrong with you that needs fixing, etc.
Forget it.
You have other friends. Focus on developing the relationships you do have, rather than trying to salvage unsaveable ones. She's gotten over you; the sooner you get over her, the better.