To forgive somebody is to say one way or another, "You have done something unspeakable, and by all rights I should call it quits between us. Both my pride and my principles demand no less. However, although I make no guarantees that I will be able to forget what you've done, and though we may both carry the scars for life, I refuse to let it stand between us. I still want you for my friend."
To accept forgiveness means to admit that you've done something unspeakable that needs to be forgiven, and thus both parties must swallow the same thing: their pride.
This seems to explain what Jesus means when he says to God, "Forgive us our trespasses as we forgive those who trespass against us." Jesus is not saying that God's forgiveness is conditional upon our forgiving others. In the first place, forgiveness that's conditional isn't really forgiveness at all, just fair warning; and in the second place, our unforgivingness is among those things about us that we need to have God forgive us most. What Jesus apparently is saying is that the pride that keeps us from forgiving is the same pride that keeps us from accepting forgiveness, and will God please help us do something about it.
When somebody you've wronged forgives you, you're spared the dull and self-diminishing throb of a guilty conscience.
When you forgive somebody who has wronged you, you're spared the dismal corrosion of bitterness and wounded pride.
For both parties, forgiveness means the freedom again to be at peace inside their own skins and to be glad in each other's presence.