He's just wanting to blame you for his failures in life. Perhaps as he progresses along with AA he will come to terms with his role in his failures to be a responsible man and stop blaming you.
Keep attending Al-Anon. You don't want to find yourself down the road repeating past mistakes with a new addict.
Blessings to you and your child. I hope your mother will welcome the two of you and you can make a fresh, new start to a better life.