Socratic you are right, you forgive someone because it hurts you not to. I heard someone say it is like taking poison and expecting the other person to die! You only hurt yourself.
It doesn't really have to do w/if the person deserves it or not. With God's help I forgave my dad for years of abuse and wrote him a letter telling him all how I felt about how he had treated me but in the end I forgave him. My dad to this day has never acknowledged he did anything wrong but my heart remains at peace. It isn't about the other person changing it is about you changing. The only person we can change is ourselves.
For me though I struggled for years to forgive my dad, I knew it was only hurting me but like you said, you kind of feel like if they deserve it and you forgive then you are letting them get away w/hurting you. Finally I realized that by not forgiving I was in bondage to my dad and was allowing him to still hurt me.
Although I have forgiven him and let go of my anger, my dad has not changed and because of that I do not go around him or put myself in that situation where he can do something to hurt me. I think you can forgive but that doesn't mean you just trust the person now. That is something that must be earned back. You just don't carry that hate or anger towards them anymore. :wink: