What is your advice to a remorseful girl who sent her pictures to young men via Facebook, and feels fear and anxiety about her pictures being exposed despite years having passed since then?

You must stop sending pictures, and your fear of their impact and spread is valid. It should be a motivation to strengthen your connection with Allah and seek His concealment. As for the negative, obsessive fear, it is treated by ignoring it. Sincerity with Allah in repentance and steadfastness is sufficient. Beware of contacting those to whom you sent the pictures to request their deletion, fearing they might exploit them for pressure or blackmail. It is advisable to forget the matter and devote yourself to study, worship, and steadfastness.