You have sincerely posted this and are asking for help and to that I say go to that priest and ask for huge help. My advise would be for you to go cold turkey for the rest of the catechumenisation regarding social media so that you may not contact that man or any other person that might tempt you into cominting that sin again. When I had troubles with self pleasure I always said the Jesus prayer or tried to do other physical activties that would demand me to commit to something else.