It is going to be very difficult for your relationship until he can discuss his condition. As his legal case progresses, there should come a time when you will have access to the medical diagnosis of his current condition. Until then, it will be like trying to nail jello to the wall.

We struggle enough trying to understand our own condition. One of the starting points to getting on with our lives is that point in time when we fully understand our dysfunctions and limitations. Then, we can start to learn ways to work-around those dysfunctions.

Your goal should be to understand what parts of his behavior are caused by his injury and what are part of his pre-existing personality. Then hopefully, you can come to an agreement with him as to how you can help him.