It will be a part of him forever, esp if he has to work hard to stay clean and sober.
There is a lot to think about from your end and your end only.
It is very easy to get sucked into that 'world' but try your hardest not to. Stay you! Don't lose yourself is what I'm trying to say.
For me, the less thinking and figuring out I do, the more peaceful I feel. I have a hard time with taking things slowly. It is helpful to respond to your post and remind myself of this too.
One day at a time.
Breathe.
Live your life.