this girl thinks I want to be her friend?

[𻇪৙𻇪৙]

I was friends with this girl a few years ago but our friendship ended really badly as did her friendship with my friends. I changed my profile picture on Facebook yesterday and she commented on it saying she missed me and then sent me a really long message about wanting to be friends. I was trying to be polite and kindly told her that we are strangers now and if we tried to be friends again that I wouldnt know where to start.

Truth is I really don't want her in my life anymore. She took the message the wrong way though and thinks that I want to be her friend again. I feel like I've backed myself into a corner. How do I tell her that I really don't want to be her friend?