Yes, since she has your address maybe you shouldn't be that harsh. Who knows, she might send you a letter.

You could block her emails to avoid the curiosity of reading them. If I were you I'd be tempted to know what bullsh.it she's talking about before deleting, so blocking may be better. If she PMs you on facebook, just tell her you're busy or ignore. Chances are she'll get tired of you and the friendship is over.