Hey.
Sorry about the situation
Unfortunately it reads as if your partner is cross addicted – using the things you described to self medicate somehow.
Perhaps seeing what he saw sent him that way, who knows. Unfortunately what I do know having been in his shoes is that unless he wants to stop all this himself and get help, there is nothing you can really do other than look after yourself. Feeling sorry for him isn’t going to help him long term either.
Would he consider seeing someone to get some outside help ?