Letter to the toothless monster

As a part of healing myself, it has been suggested that I write letters to some people who I can't say what I need to say in person either by death or because it will cause harm in some way. I am currently trying to write one to my abuser and I have writer's block. It was easy to write about what he did to my little sister, but when it was time to start about myself I couldn't think. I have thought to pick up and try again for days now but I can't seem to find the courage to do so. Perhaps I am scared that the pain I already feel will hurt double that. Maybe I am just not ready to face this or I am not willing to let go of this anger, hatred, and the blame and shame I have put on myself. That would be crazy though, right?