Forgiveness is not about forgetting.
Forgiveness is something that you do for yourself. Harbouring old hurts only wears you down emotionally and sometimes physically (causing medical problems). I think that you can take this in steps. Baby steps maybe.
What if you went to see him and told him exactly what he did to you? All the hurt that he caused you emotionally, physically, mentally, etc. You don't necessarily have to be confrontational about it. Just bring it up that he REALLy hurt you and that it has affected your life. Facing the fear (of him) should help to dispell it. If you are still scared of him, he still has a hold on you.
Then maybe you will be able to forgive him. But you don't necessarily have to tell him that. See if he is truly remorseful. See what kind of person he is now. And take it from there.
I definitely think that yo've been given the chance to face him and clear up these old feelings. And to give him the chance to be remorseful... if he's grown at all.

KP... No one can tell you what you should or should not do. We can be here to support you in whatever you decide to to. For me, I don't forgive for the other person, I forgive for me. I look back at things that have happened in my life and wonder how I can forgive the wrongs done to me when I was growing up, but then I realize that I am a better person for having forgiven the people involved in those major incidents. I wont ever be able to completely forget them, nor do I think I want to. They shape me, good or bad, into the person I am today.

Perhaps him calling you was not for you to help him, but in some small way a chance for you to find closure on the past hurt, for you to realize that you have grown, that you have become the beautiful person you are. That you are so much stronger now than you realize.

Here if you need me. I love you *hugs*

If only we could forgive on command or forgive simply by virtue of wanting to forgive. You certainly do not owe this man any forgiveness but I agree with Heather that maybe this man coming back into your life is some kind of sign that you still need some sort of closure, forgiveness or otherwise. Maybe you need to face your feelings for him in some way whether or not it ultimately leads you to forgive him.

you've been given good advice here- these are excellent comments. Let me just add some practical ideas- sometimes the easiest way to forgive is to turn your anger to pity- realize that he has to live forever with what he is, and what he is will never bring him peace. Pity him- and then he's easier to forgive. That's how I was able to forgive someone who did terrible damage to me and my family. And then tell yourself that he has no right to mess with your head like he is, and you're not going to let him. and as Heather says- let the lessons learned shape your life for the better.

there is nothing more to add, you received some fantastic comments, but hearing all this great advice is one thing, following it is another.