That Bridge Done Burnt Already

Internet social convention is to not write details about issues or complaints that are workplace related. 

However, what do you do when the complaints are about a former client or employer.
And what if that former employer or client has already blackballed you, therefore making the argument about future employment moot?
And what if your complaints about them are about what's been done AFTER your business with them terminated?


Are you still supposed to remain silent?