Do I have legal recourse if I was wrongfully accused without opportunity to respond?

I was accused of violating student confidentiality. I was written up and threatened with dismissal without any opportunity to respond. When I told them I had never broken student confidentiality and asked what proof did they had, my boss just asked me to sign the document they had presented. I offered my 'quiet' resignation if they would clear my record and they refused. I resigned due to the impossibility of completing the terms of the disciplinary plan. Do I have a case?