He has the appearance of someone who is abusing some substance, what it is doesn't really matter, the important thing is that you know this isn't right and don't have to be part of it...even living in the same house.
I learned a long time ago not to engage someone who was using anything, arguing with them makes it worse, trying to reason with insanity is futile and only make ME crazy, and trying to change what was not mine to change wore me out.
The best way to live with this is to live your own life, find your own peace and happiness and pray for the loved one who suffers, leaving the rest to God.
Hope today brings you joy and beauty, it's there when we look for it.
Hugs