You look to be on top of things. Sad you have to deal with it with baby so close. Yes, I get it now. You want to support change but let him know your bottom line. I think your doing it. I guess being open to listening to him and encouraging him to seek out help if he has trouble quitting. Real addiction, especially if it progresses often requires more than willpower. Many times people must get help from a doctor or addiction therapist who will help create a plan.
But your doing great. Hope he appreciates your strength and love.