First I'll start with a reality check- I lived with my alcoholic/addict ex until our daughter was 17 months. I moved when social services became aware of the domestic violence and drug abuse going on in our home. They told me it was him or my baby, if I stated they would take her away. That is a very very real risk in this situation, it only takes one event to trigger the social services involvement. I don't mean to sound harsh and you might not even accept this reality, but for me it became very real. Even more real this week when I met ladies who have lost their children to the care system because of these very situations.
Have you seen a counsellor or gone to a meeting? I see you're in the UK, I attend families anonymous and it's been AMAZING. It's seriously changed my life.
His family don't live in your home and don't know the reality of your life. Dont let them manipulate you. You're not responsible for the actions of a grown man, he does exactly what he wants to do. You are not powerful enough to make him drink or not drink.