sudo: /etc/sudo.conf is group writable

I've made a mistake. List of commands that I typed:

• sudo usermod -a -G root erp
• sudo chmod g+w /etc
• setfacl -R -m u:erp:rwx /etc
  
  

Then ssh.service of the virtual machine stopped working and when I type commands with sudo in terminal, it says sudo: /etc/sudo.conf is group writable.

And after googling for some time, it seems what I have done is similar to chmod -R 777 /. I'm hoping that I don't need to reinstall the Ubuntu OS on this machine. Is what I have done actually revertible?