You will not have peace. The greatest feeling of peace comes to us after making a good confession where we know that we are reconciled to Jesus. Peace can only come from a right relationship with God. Sin hurts our relationship with God. Sin hurts other people.
Sins hurts the sinner.
Jesus does not desire that we be locked up in this fear. He has given us the gift of the Sacrament of Reconciliation to be freed from our sins. Another problem we battle in our lives is doubt. In the Gospel today we see Thomas struggle with these same questions. He had invested three years of his life to following Jesus and now the Master has been killed.