My lawyer was very reassuring about my ability to maintain physical custody of my son.
BUT...
She emphasized the importance of having evidence regarding his alcohol abuse:
rehab bills
court documents
records from counseling sessions
photos of empty alcohol bottles
letters or email in which he admitted "the problem"
AND...
She made it clear that divorce doesn't separate children from parents, even if one parent has physical custody and the other is an alcoholic. The courts still tend to rule that a child's best interest is served through active involvement with both parents. If the judge knows that alcohol is a major part of the equation, the visitation schedule can be adjusted to protect the child (i.e. supervised only, no overnights, etc...).
All that to say, there was a time when I thought I should just get a divorce and completely remove my AH from my life and my son's life - the legal system didn't share my enthusiasm for that plan.
-TC