You need to have a serious talk with him. You've got to explain to him that if you two have any chance of making this work, he has to first forgive himself and start moving forward. Tell him that if he can't do that, then there is no use in even trying, because he is dooming the relationship before it even gets started. Maybe you need to give him a week or two for him to reflect and decide if he thinks that he can even commit himself to the relationship, or if he chooses to live in the past and keep bringing it up.
