I've just lost my best friend

I've just received a message from who I thought was my best friend of over a year saying that, although she thinks I'm 'kind' and 'always want to do my best for everyone' I'm also 'too emotional' and 'downright annoying' (these are all direct quotes) and she never wants to speak to me again; she's asked me to not to contact her. This has come out of the blue; I swear I have done absolutely nothing...or at least I don't think I have. She didn't say I'd done anything, just that she 'doesn't like my personality' and she hopes I'll 'cherish the memories of our friendship, even though she doesn't want to be friends anymore'.

This has sent me into a spiral of despair, but I know she has every right to end the friendship if she's not happy. Am I overreacting? How will I get over this? Am I going to fail every friendship I'm in for the rest of my life? It's devastating, and all the worse for having been given no right of reply and no clear explanation, apart from the fact that 'she needs to concentrate on herself and I'm too emotional'. Which I suppose is fair enough...do I have a right to be upset?