Do I need an attorney at my hearing for selling a alochol to a minor?

I had been working with a grocery store for over 14 years with an unblemished record, and I had never been in trouble for anything in all my life. A few weeks ago, I was the victim of a sting operation and sold beer to a minor who had a fake ID. It was also an ID from another state and though I had never seen one before, and it appeared suspicious. My new computer system at my check out station permitted the sell. First of all, I had never been trained to recognize the difference in fake IDs even though the store had the opportunity to train its employees (I found out later)and chose not to. I was terminated last week as of policy. I now, for the the first time in my life, have to go to court and pay a $675 fine, plus it could stay on my record. I surely can't afford high dollar attorney, yet I feel I was unjustly terminated. I understand there is what's called a pre-trial diversion that can take my lifelong work and criminal record into consideration. If anyone reading this can help in any way or has comments.. Please leave your comments soon. I have to appear in court on the 19th of this month. Thank you so much for this website and the free legal information.