It is ok for you to let him know that you are happy for him. But please think along the lines of "you divorced me; you can't have me as your best friend anymore if you want to be divorced."
I know it is hard to see where you are right now.
Does he get text messaging? You could avoid talking to him on the phone by just sending a text "Congratulations!" and leave it be....I know it is hard but remember: all WASs seem to think that we will still be their best friends post D! crazy talk!
me,34 exH,34 S,16 months S:3/31/09-left for OW started DBing 10/09 d final: sometime 10/10 current: http://www.divorcebusting.com/forums/ubbthreads.php?ubb=showflat&Number=2022856&page=1 met in 2004