I disagree with NEVER having coworkers as friends. However, I admit that, on the whole, it's a good rule of thumb to work by. I have long term friends that I met through work years ago that are some of the best people I've ever met. They never betrayed my confidences at work, and have not betrayed my confidences since. You will find untrustworthy people everywhere in your life, it's just part of the process of building your circle of people. And, honestly, any time you work in a small environment like that, with only a handful of employees, everyone typically know everything about everyone.

It's never easy getting fired. Grieve while you look for a new job. Take it one day at a time, and you will find yourself in a new and better place. Good luck!