The problem that you now have about the situation about the broker's fee and the remaining $1,300 allegedly owed is that you have already paid $5,000 of the $6,300 amount. By paying any portion of the $6,300 amount, let alone a substantial portion your actions indicate an obligation owed by you for the brokerage fee regardless if you wife's name is not on the lease where the brokerage claims money owing.The reality is that you paud $5,000 and are living in the unit subject to the brokerage fee. Unfortunately for you, by your own conduct it seems that you owe the $1,300 balance.