Yes, seems inappropriate. He is a grown man this will need to be his choice. His sister can be an enabler, but this is really about... YOU.
There are ways of handling this. You can get angry, yell, force.. etc.. IMO, This will not work. It will take some actions.
Have you had enough? Can you protect yourself enough to start some pressure.. or even an ulimatum, your call since you know your situation the best.
Here are some thoughts... Under control, not rattled.. planned and short and sweet. Add some pressure.
Pressure.. light pressures
Close marriages do not include addictions, what can I do to help you?
then move to heavy pressures...
I am not going to be in any relationship with addictions. Either you quit, or I must move to a safer place for me.
When you get sober, only then will I be around you. Bye.