I hear you.
I don't think I would tell DC yet until after the eval, and then, only tell him portions of what might be relevant.
Perhaps just say... going to a doctor that specializes on how the brain works. We're going to see what our strengths and weaknesses are... just do your best.
There are lots of other people with Aspergers, ... and it is just different. Would there be a silver-lining to this cloud? Perhaps mention those. ? Maybe don't give him the word "Asperger" yet...
Hopefully someone else will chime in with better ideas.
Take care,
