Hi,
I have been recovering for a very long time and only recently has my son begun to get help for himself. So I am learning the same lesson's you are. I am inclined to catch him while he is sober and thinking and unload all of the stuff that I have had pent up all these years. But I, like you, am learning that it is selfish not supportive. I have to, like Ann said, let it go. It serves no purpose and it only perpetuates the bad in our already strained relationship.
I have written a couple of letters...neither of which I have mailed. I am not sure it helped but it felt good at the time. Maybe a journal could be your outlet.
Hugs,
JT