Hi & welcome -- and I'm sorry about the heartache you're going through.
But your actions and decisions are those of a healthy person. And that, you should be happy about. That you were able to disentangle yourself before his addiction started affecting you negatively in a profound way.
You seem to have a pretty clear understanding that his alcoholism is his problem, and not something anyone else can solve for him. You're absolutely right in that. Many of us who ended up in really deep trouble didn't realize that, but were convinced that somehow we had the superpowers to help our loved ones get sober. Rest assured, you haven't missed anything. Love doesn't heal addiction. And when I left the alcoholic I was married to, a friend from Al-Anon told me that "you may just have done him the biggest favor anyone ever will" -- by NOT trying to cushion the consequences from his drinking anymore.
Alcoholism is a progressive disease; without treatment, it only gets worse. As they say in AA -- alcoholism is an elevator that goes down to hell; it's up to you what floor you want to get off.
As much as it hurts to leave someone you love, you chose to get off fast when you saw where the elevator was going. All I can tell you is that it wouldn't have gotten better, or easier, if you had stayed on. It would have gotten much worse, and harder.
Hugs.