I was fired for no reason and after I was fired other employees for the company were told by my ex boss that I had it coming and that I was a jerk. I believe more than just that was said but I have not questioned all those that I worked with. Can my ex boss do this? Or does it violate some sort of confidentiality?

Your boss is entitled to his opinion. Discussing such matters is not very professional, but it isn't illegal.

thankyou...