Jesus shows the steps to restoration. The slave admits his debt, but it is interesting to note that the slave doesn't admit his inability to repay. The master released him from the debt. He doesn't have to repay. This is a great illustration of what it is to forgive.
People are confused.
They think that forgiveness equals forgetting. But it doesn't. You know they owe you, but when you don't make them pay, you know that it cost you. The slave turned around and refused to forgive another slave a debt owed him. We are so much like this slave.