How can a girl deal with an unknown unseen hacker stalker and harasser?

If you are old enough, and a law abiding citizen of the United States of America. Apply at your local police station for a gun permit. They will ask you the reason, and you reply for all lawful & legal purposes only. You should maybe try to take some self defense classes. Move to another location, try a Post Office box. Don't leave a paper trail, be very careful how your information is viewed and used everywhwere. The first thing to do though is call your local Police and file a police report!