jay,
Your post touched my heart. I came home when my son was 6 months old and found him and my AH the same way you found your wife and child: The "responsible" adult passed out drunk, the baby having the free reign of the house.
It took me another 16 years to get out of that relationship. I feel like I can breathe easier knowing that you won't have to live in that hell, and that your child will not have to suffer the way mine did. Thoughts & prayers & good vibes & whatever good thoughts you prefer go with you.