Fact is the worst thing you can do about this kind of stuff is to get upset about it. Sending a message asking to remove them is good, albeit it only once. No use spending all this time and anger in repeated requests. Reporting the abuse if the platform supports it is the next step (also try to do this without anger, just with rational logic). But don’t get into a p*ssing contest on Twitter, FB or whatever. Just ignore. THE moment you feel the need to defend yourself and enter the “discussion”/shouting match you have already lost.
I like the idea of putting something on your facebook page telling YOUR people what happened (short, to the point without emotion and without pointing people in his direction – they WILL go check it out for themselves if you do and that would be counter-productive).
This guy is not important and HIS people are unimportant to you as well. So don’t waste any energy. This is the internet, people will try to mess with other people all the time. If you react your give it validity and power. So, don’t!
I understand the feeling of needing to retribute, but it is really not helpful. Inform your people without going into a rant and be done with it. Move on and focus on putting energy in all the good things in life and become an even better DJ.
Just my two cents of course.