My feeling is, he does care and feel things deeply but he is self medicating in the wrong way.
He needs professional specialist substance abuse support which inevitably involves some level of counselling, but counselling alone without a real focus on how he is managing the drink and prescription? medication will not suffice.
And him unravelling in the same home as you will be hard to manage around the kids.
And you need to put your life jacket on first before you save everyone else.
Stopping drinking suddenly can be dangerous and cause seizures if not supported with medication.
So get some professional help from your local council website.
No idea where you live.
You sound American in your lingo, but wherever you are, there will be online/telephone help you can look up.
Maybe start with Domestic abuse services online and look for links to substance misuse services.
You may not want social services getting involved but they may be of use, and may end up involved anyway because kids get caught in the crossfire somehow.
You best be proactive now so you are seen as wanting to protect them, and improve their father's life so he survives to bring them up.
Maybe you suggest he gets bloods done to check liver, kidney function.
Get a liver scan.
Speak to your doctor?
Loads of help out there if you look for it. But professionals will be wanting to safeguard the kids and escalate concerns if they have any, re kids welfare.
If you are seen as a protective factor, then hopefully things will work out the way you hoped.
But he sounds pretty well hooked atm and no shifting his position long term.
He's an adult, remember that.