Your post makes me think of one relatively effective communication strategy with someone who is afflicted by substance addiction can be to focus on the negative outcomes of their using behavior without attacking the use.
I’ve found that sharing the facts of how events played out can be a useful way to explain to the person the reality of how their behavior is actually unfolding and this highlights the problematic nature of their substance use without having to specifically attack the use.
Timing for these conversations can be key. When are we better heard? (Eg. it may be when they are sober, not hungover - can be different for each situation.) Notice how striking up these conversations can be met with resistance when we are still in the heat of things.
Also, I found in my relationships that saying something like - you’re not able to remember clearly the details because you were under the influence. Can help also.
Any updates since you posted this @dont_wanna_say - love to hear more <3