Snowfall - My husband also almost drank himself to death at the age of 38 - coma, heart attack, diabetes, pancreatitis. I was not around then so I am not sure what the catalyst final "clarity" moment was that happened that he decided to get sober I do know it took two years before he did.
Last year he relapsed after 10 years sober. Alcohol is a death sentence for him with his physical issues. In as much as I didn't want to be around his drunk behavior a greater motivation to leave the relationship was that I didn't want to watch what would be equivalent to a partial hanging death, or disabling himself to the point of who knows what? Dialysis? another heart attack? Amputation? Stroke? No thanks - not if by your own doing. Thankfully he chose sobriety again over that.
As hard as it is you are doing the right thing. Prayers for you, your son and your ex -