To protect oneself from blackmail for sex stories, start by maintaining strict privacy. Don't be too trusting with people you don't know well when it comes to personal and sexual matters. If you suspect someone might be trying to blackmail you, document everything related to their threats. This could include the time, date, and what exactly they said. It's important not to let fear control you. Instead, rely on the legal system. Inform your family or close friends so they can support you during this difficult time. And most importantly, don't let the blackmailer's threats force you into any actions you don't want to take. Report the situation to the police as soon as possible so they can start an investigation.
One should never share overly personal or compromising information in the first place. If faced with such blackmail, don't give in and immediately contact the police.