If you are being prosecuted by the da, and you want to counter sue the original person filing the claim who do:
It can't be handled in one trial.  Theft is criminal, and malicious prosecution and breach of contract are civil.  The DA won't touch them.  If you don't have a lawyer to bargain with the DA, then your best bet is to sit tight, gather your evidence, and defend yourself at the criminal trial.  If the DA wins, your case may be sunk; but if the DA loses you will be in a better position to sue the witness whom you believe lied.  You can sue in civil court, and you might be able to sue in Small Claims without a lawyer.