Do not engage.
Block phone numbers, emails, social media contacts. Delete all contacts for person. If more messages are received, continue to delete and block- do not respond no matter what. Do not read/listen as soon as you have identified the caller/sender.
Do not ever open your door. File a personal protection order/restraining order and report Every violation. Ignore completely in public places. Report harassment to management/security/police, as needed. Assert your right to be safe in your own home, and in public spaces.
Do not violate order yourself by calling, texting, emailing, messaging, or otherwise contacting abusers for Any Reason! If you feel a strong urge to do so, call a safe friend, or an on call service you are engaged with, or a crisis line for your area. This is a True Emergency. Treat it as such.
Longer term goal - work on building a network of safe friends. I am not so great at this myself. But, i would Far rather have 1 safe person to call on than 100 unsafe people.