separation from mother
Questions in the Autism & Asperger's Syndrome forum are answered by researchers at the New England Center for Children. Topics covered include Attention Deficit Hyperactivity Disorder (ADHD), Antisocial Personality Disorder, Asperger Syndrome, Autism, blindness, bullying, clinical depression, deafness, dyslexia, mental retardation, and social alienation.
Have you spoken with your ex-husband as to the reason why he is denying access? There have been other parents in a similar position who have posted about how the childs behaviour gets out of control when they are going to visit the other parent or when they come back from the other parent. As you are reading up about ADHD and Aspergers you will understand the difficulties these children face with any change or unpredictable outcome. They also take things literally and therefore alot of things they may see or hear whilst their parents are separating could scare them. The whole idea of their parents separating will make their world a very insecure place. It may be that on times when you have seen your son that the emotional turmoil of being in a 'separated' situation has meant he has been very upset or physically violent on returning to your husband. Obviously you won't know that unless you are in discussions with your ex-partner. I am not condoning the the fact that he has denied you access, but he must have a reason as to why he thinks contact is not beneficial to your son. And when you know what that is it will give you something to work on.
If you have discussions and it is your son's behaviour that is causing your ex-husband concern you could suggest seeing him at your ex-partner's house if that is a viable safe option for you. That would mean your son is remaining in his familiar environment.
Regarding the legal side of the access you will probably have to see a solicitor about that.
As the parents you could also consider your son seeing a psychologist who has experience in ADHD and Aspergers who could see your son and give you both some ideas of what to be working on.
Play Therapy can also be a good way for children with ADHD/Aspergers to help them deal with emotions, enabling them to air their feelings with a therapist who will help them come to terms with how they feel about the whole situation.