If, in fact, the person you signed a contract with had no legal right to enter into a contract for this property, then this is criminal fraud. I would go to the police immediately. Then sue. But if this person did commit fraud, the likelihood is you are out the money unless she has assets you can attach.
I hate to mention this but you should never sign a contract without legal advice. Had you engaged an attorney he would have made sure the woman had title to the property.