sandy, been there done that and going through it to this day. i would have to agree with arcturus when he says that you can't forgive this man, only God can grant you that and when He does, you'll know it.
the experiences that i have had with this, and there have been many, is that praying for the individual leads to something of a revelation about them and me and God's working in my life, which then leads to compassion for them where they are, which then leads me to thankfulness for the Christ and God's mercy, which then leads me to the sermon on the mount and the story about the man indebted to the king who has that indebtedness forgiven and so on.
know that God will walk you through this. if you don't have the "experience" of mercy yet it is because He does not want you to experience it yet. it is His desire to do so but the timing is His. there have been times when i have been given that grace immediately, there have been times when i have had to wrestle with the emotions for some time. i am currently in the throws of a situation where mercy, grace and compassion are part and parcel of the battle. there is something else in this experience as well, but that is a discussion for another day.
don't lose heart. these are the experiences that ultimately lead to the deepening of our hearts and minds in His love.