It can be difficult to forgive those who use their free will to hurt us. It might be difficult but as we learn in the lesson of the Master who forgave 10,000 talents teach us, we will only be forgiven the sins we commit against God if we forgive even the smallest sin someone else does against us. We can never repay God what we owe Him. God has given us everything we have ever done, but He will forgive with mercy and grace, but only if we have also forgiven others.