The first thing I thought of when I read this post was, "don't cry over spilled milk".

That is to say, your husband is 100% correct. Your dad should have stopped drinking. He should have not abused medications. He should have this, should have that, etc.

But he did NOT, and now he is very sick, and that's the reality you have to deal with now. He already knows this is his fault, criticizing him and not providing support for this is useless. It'd be like telling someone dying from lung cancer that everything is their fault cause they smoked, so you're just going to be angry and now hold their hand as they pass away.

The only thing this is going to do is bring more pain into the world. The time to pressure someone to adopt a healthier habit is before something like this happens, and after they survive something like this. Right now though your father needs help and support, and you should tell your husband that choosing this time to become irate about your father's poor choices is inappropriate and/or useless and unhelpful.

Your husband is 'right', but sometimes being right doesn't mean that your behaviour is necessarily helpful, which is the case here.