Seriously people blaming Dan doesn't understand how addiction works. It's often a symptom, not the initial problem. Trying to make him stop alcohol while JK is still around and still treating him like shit doesn't make sense! He is the problem here and has no fucking right to be frustrated at him.
The vision we have on alcoholism is seriously dumb and not helping at all. I don't get why so much people are blaming the sick person and not mister self-centered who doesn't realise or doesn't care about the bad things he does to people.
If a victim of abuse has fallen into drugs, try to stop the abuse first. The drug is not the initial problem it is a symptom. Then stop drugs will be a bit easier (not easy but still easier).