It is very important to stop it quickly. You can remove the personne harassing you from your friends list and report it to Facebook so that they can take action. You can also file a complaint to the gendarmerie brigade or a police station of your choice
https://www.interieur.gouv.fr/Contact/Contacter-une-brigade-de-gendarmerie-ou-un-commissariat-de-police. You can find more information by clicking on Next link:
Harassment online .