in my opinion-
this diagnosis doesn't change anything.
He has learned to adapt, self medicate with the alcohol.
After a certain time - and if this all happened when he was young- it likely has been awhile - you are fighting many years of a behavior that he has come to accept as normal.
You have to get past the alcoholic to get to treat the post-traumatic-stress-disorder. Even though the alcohol use was likely brought about by the PTSD.
In my AHs case - he could never do that.
AH was a victim of child sex abuse by his mother's boyfriend when he was 11 years old. It took him 25 years to admit that to anyone - and even though he has gone to some therapy related to this - (and a ton of detox & inpatient treatment for alcohol) - he still continues to be an alcoholic.
Good luck to you & AH