Gosh I think when the roles in a long term marriage change significantly its always hard to readjust.
Thing is he can't make up 18 years to you in a time exchange. The only thing he can do is work his program and stay sober. I am sure that is what you have prayed for and now its happening. At some point you will need to address if you can forgive him for what he put you through. You guys just aren't on the same timeline and that's ok. His sobriety doesn't immediately erase the resentment, anguish, and fears that is something that you will have to work through on down the road.