You're in a relationship with someone who almost certainly is an alcoholic. A litre of strong cider is 7-8 units of alcohol. So say he does two litres a night, five nights a week, that's a minimum of 70 units a week. It's entirely possible he's doing more like 100 units a week. For reference, any more than 35 units a week is generally considered to be a big flashing warning sign of an alcohol problem.
Another important thing to consider is this; he drinks two litres of cider. That's (say) 15 units. He goes to sleep for (say) eight hours. The liver deals with, on average, a unit of alcohol an hour. So when he wakes up he's still half-pissed. Does he drive? Because if he's breathalysed in the morning there's a very good chance he'd fail.
Alcohol problems tend to get worse over time. The mental and physical health problems associated with regular heavy drinking add up. Anecdotal evidence suggests that a lot of people can more-or-less keep it together despite their heavy drinking until they hit their forties at which point the combination of increasing drinking and decreasing health can make the shit hit the fan in very short order. How old is he?
There is absolutely no point whatsoever in having deep and meaningful conversations about your relationship with him when he's been drinking. You're wasting your time and breath. You might as well be talking to the cat.
To be honest there's precious little point talking to him about his drinking at all. You can't talk an alcoholic into stopping drinking until they reach the point where they've decided that they want to do something about it.
But don't think that your children aren't aware that there is a problem. They may not know that it's to do with their dad's drinking but they will know that, sometimes, you could cut the tension in the house with a knife. And as they get older they'll see, and hear, more and more.
I thought that my children weren't being affected by my ex's drinking. I was wrong. It was only when we split up and my children emerged from the shells I didn't even know they were hiding in that I realised just how much they had been affected. Our home is now calmer, my children are happier and more secure, and my ex is still a piss-artist.
Being a single parent can be tough and lonely but I guarantee you that raising kids with an alcoholic was far far tougher and a thousand times more lonely.
Your husband's drinking is entirely his own responsibility. You didn't cause his alcoholism, you can't cure it, and you can't control it for him. All you can do is decide if you want to be in in a relationship with someone for whom alcohol comes first place and everything else comes a very distant second place.