I applaud you for being there and wanting to be a good supporter.
Read both personal stories and articles or books that offer coping and healing techniques as well as those that describe the healing process.
Be ready for the things your husband is going to have to go through, mood swings, acting out, being triggered, etc...
The more you learn, and prepare for, the less you will blame him for things that are going to happen. You will understand that it is because of the abuse and, because he is trying to work through it, not because he means to hurt you. And trust me that will happen, but if you know why, it's easier to deal with.
I am both a survivor and a supporter and, being able to get through the times when your survivor will hurt you ultimately builds a closer relationship, if you can ride the storm with him. It is never easy to stay there when it gets rough, but it's worth it for both of you.