The Apostle Paul and the doctrine of forgiveness?

Alexander the metalworker did me a great deal of harm. The Lord will repay him for what he has done (2 Timothy 4:14). Forgiveness is central in Christianity with all the great churches.Jesus own words:Forgive them father for they know not what they do. Here we see the Apostle Paul speaking about "repayment" for harm done to him. What is the Catholic doctrine on this verse or how one is to understand judgment vs forgiveness in this verse?