RED ALERT! Concert Josh Need's HELP!

Does anyone have any advice on how to get rid of an internet stalker? I have tried everything I can think of, and this person still finds the need to contact me. She had to email me to let me know she saw my 'twin' today.. "if it wasn't for a distinctive mark on his right arm about half way down his bicep." Now that is too much detail for me NOT to be afarid.

This is starting to freak me out. Soon she will be a real life stalker, and I don't want to die yet.

Please help me out here, and let me know what you did to rid yourself of a stalker.