You are an attorney. A former client has fired you because of what he claims are "personality conflicts." He refuses to pay you the remainder of the legal fees you are due. A prospective client desires to retain your services to file a suit against the former client. You are more than willing to help the prospective client obtain a judgment against the former client to get even for the former client's behavior. Is it ethical to represent the prospective client and use your information about the former client to the former client's detriment?