Forgiveness is free in that the one who forgives may do so unconditionally whenever he or she is ready. There is no need for the offending person to apologize or to make recompense of some kind before you allow yourself to forgive. If you had to wait for the other to show remorse or to say certain words, then forgiveness is not freely given…….and then you are trapped in unforgiveness until others decide to do what you think they need to do to set you free. Is this not another injustice against you? You are bound in unforgiveness until the other lets you out of that cage of resentment. So, you are right that forgiveness is hard work and that is the “cost” to which you refer, but forgiveness is “free” in that you may do so when you are ready.