I'm going to hazard a guess here that this never would have happened. If he couldn't cope with seeing you more than once a week (no reflection on you btw) then there is NO way he could have a real relationship full time.
If for some reason you did get married and have children, how on earth would he cope with that? Basically you would be a single parent. People don't change that much you know? I mean some people can overcome personality disorders or addictions or whatever but that takes commitment, hard work and a real willingness to do that work. He is conquering the alcoholism which is truly great but the underlying problems are all still there, whatever they are (which he never told you).
You spoke about having children and then 5 months later he backed out on that. Did he ever bring it up between the time you initially mentioned it and his announcement 5 months later that it was a no-go?