No one can chat.

Every time someone types something they get the console error:

FCVAR_SERVER_CAN_EXECUTE prevented server running command: say

Any ideas?

You might be infected with a malicious script, perhaps?
Look in your lua folder for anything suspicious.

Garry fucked up trying to make a whitelist system.

I say do a blacklist AND a whitelist.
If both commands are on the blacklist AND whitelist, blacklist the command instead.

L. O. FUCKING. L.

and caps

Remove addon GME chat, it fucks up your chat.