I still think you should wait to hear back from the therapist. He is the one that is working w/your son at the moment. He will be the one to gently listen and help him work through his emotions/feelings.
Gerda, try to remember that you can't control your h or your s when it comes to their relationship. Yes, you can gently guide your son, but there will be a time that you need to step back and allow your son to decide what is best for him when it comes to a relationship w/his father. That may be discussed in a session w/his therapist sooner rather than later.
You have nothing to fear, but fear itself. You have to trust that the system will work and have faith in the man above, as well as in yourself, your son's therapist and your lawyer to do the right things. I know that it looks bleak at the moment, but there are times when you have to just let go and allow things to progress and if he needs you, he knows that you will be there for him.
Sit quietly, the answers will reveal themselves when you least expect them to. The past is gone, the present is a gift and you need to focus on today, allow the future to reveal itself when it is ready.