First, I would pray daily, and often throughout the day, to our Blessed Mother and ask her to show you how to parent your son. Ask her to show you how he is feeling, what he needs, and what he doesnt need. Ask her to guide and bless all of the interactions between the two of you.
Second, is your schedule similar to what it was before your husband died? Does your son know what is happening on a day to day basis or does it change often? Sticking to a regular schedule (you may do this already) can help ease some of the anxiety. Hanging the schedule for him to see would be good too. Make sure to include the family time that others have mentioned.
If you have to keep telling him to do things over and over then maybe try hanging a list of what is expected of him. Of course, go over this with him beforehand. You may have tried these things when he was younger, but I would try them again.
These are just some suggestions to get a little more grounded, not meant to be fixers of the situation. But, as you know, children with Asberger's tend to need that consistency and those visual aids. Once the anxiety level decreases, that's probably when hell start talking.
Sorry that I couldn't provide more help, just my two cents. Remember that Mary is with you at the foot of the Cross.