My best friend of fifteen years isn't my best friend anymore?

[492]

I moved away six years ago at 13 and our friendship was going strong. ever since she entered university she got a boyfriend, got new friends, and doesn't even interact in the same way with me anymore. She even forgot my birthday, but filled her facebook up with statuses wishing some other chick (her "best friend") happy birthday. People are telling me to "screw it, nothing is forever" but I feel like I'll never relate to someone in the same way anymore, she was like my sister. I just feel really sad right now.
And honestly, I even confronted her about it and explained how I thought she was too busy for me, and she was surprised. I don't think she even realizes what she's doing, but that's what hurts the most because considering how long we've been friends, she should. I can't believe how oblivious she is. There's no improvement in our communication despite the confrontation.