How can I get my Facebook messages hidden from everyone?

[Izzy]

This person I used to be friends with keeps taking screenshots of my messages and posting them on his statuses and I want to get my Facebook messages hidden and say "Marked as spammed" so nobody would keep taking screenshots of my messages and I just started dating a girl I used to hate and I used to talk shit about her to my old best friend and I feel bad about the stuff I said about the girl and now my friend kept taking screenshots of my messages and posting them everywhere and I am worried that my girlfriend would think I still hated her when I said those messages months ago and I accidentally said my girlfriends secret Facebook account that she's been trying to keep hidden from people trying too troll her and I accidentally told some people what it was and I am worried that she'll never forgive me for what I did and I am paranoid that my old friend is going to keep posting my messages online and I've tried everything too get my self reported. I kept posting porn on my Facebook account so I would get reported and my account would get banned but its not working. I just only get blocked for 3 hours when I am trying to get my account banned and
Nothing is working so I really need help trying to get my Facebook messages hidden from everyone I used to talk too because I am just scared that they'll keep posting screenshots of my messages and I even tried to report the trolls that kept doing that too me but Facebook won't do shit about it D: