ok. Let's go through your post.
If he didn't drink, we would be perfect.
A lot of people come to SR saying this. Heck, I think there's a thread not too far down from the top saying "if he quits drinking, will I be happy?". Ask yourself if you love this man fully and completely, as he is today, drunken/emotional rollercoaster/passed out/chocking/notbreathing AND the sober moments as well? Because that is the only person he is willing to be until HE makes the changes himself. And even then, recovery is a lifetime journey.
His issues go way deeper than just drinking.
You're bang on here. Even if he were to quit drinking, he's got a lot of work to do on himself. That work is for him to do, not for you. If I re-read your post, I see that you are placing yourself in the position of indispensable, or "the rock" in his life. ***MAJOR CODIE ALERT*** It is not your role to lift this man up out of the supposed shackles of his poor childhood and to show him what he could be. That is entirely his job, as the grown man that he is.
Are you willing to spend the next X years of your life waiting for him to achieve this potential? I ask you this as someone who thought she saw potential in a man and devoted 6 years of her life to "being there for him when no one had", to being "his rock", to "helping him". 6 years and a baby later, he is still the same man, and he has not found his bottom. I believe he has now moved on to the next girl, and will undoubtedly find another one after that, each time leaving a child behind.
He has good intentions, and I know he always means well, but I think he is afraid of the truth.
The road to hell is paved with good intentions. By staying with this man, by continuing to provide a soft place for him to land, you are robbing him of the opportunity of finding recovery for himself. Doesn't he deserve that dignity?
Instead of thinking that walking away would be akin to "giving up on him", perhaps you need to consider that walking away would be giving him a chance to find his bottom.