That depends on the state. In my state if there is a proponderence of the evidence that a verbal contract exists that would negate the written than the new contract verbal or written would overrule the previous.To the OP have a conversation, not an argument discussing what he previously said and record it. Again dependent on your state law as long as one party knows the conversation is being recorded it should be sufficient in court, especially civil court where a proponderence of the evidence is all that is needed.