Do I have grounds for defamation law suit?

So I have worked for a company for about 6 months, the supervisor and I got into plenty of arguments and did not get along for most of the time. At some point when I thought things are going good, the supervisor called me into his office and told me that "they cannot afford me anymore and I am being let go" so I took it to the unemployment office I received my benefits for 2 weeks when suddenly it got cut off and I was told that my previous employer said I was fired and not laid off. I took it to appeals court and in one of the documents that same supervisor claimed in writing that I was fraudulently claiming unemployment benefits while working "under the table" for a different company. I have proof that I was employed only 3 months after I was let go and had no source of income in the meanwhile as opposed to his claim. I lost the appeals court and am unemployed having a tough time finding a job and am not getting any unemployment benefits. I was wondering if what was written and submitted to the appeals court has any affect on my current situation and whether I have grounds for a law suit.
Any help would be greatly appreciated.