I really like LTL's link to setting boundaries. The thing that really jumped out at me was that boundary setting is not to be used as a form of manipulation.
"Setting boundaries is not a more sophisticated way of manipulation - although some people will say they are setting boundaries, when in fact they are attempting to manipulate. The difference between setting a boundary in a healthy way and manipulating is: when we set a boundary we let go of the outcome."
Liz, you spoke of setting a boundary that you don't want to live with him if he is drinking.
So--you simply tell him. I don't want to live with you if you continue to drink. You have then expressed that boundary.
The trick is the above--letting go of the outcome. Telling him that won't necessarily change his behavior at all, in fact he may smugly sit back and watch to see what you are going TO DO about it.
How are you going to enforce said boundary?
I see this becoming a power play, a battle of wills, if he chooses to continue to drink, and you don't enforce the boundary with a separation.
The alcoholic will win at power plays. It is one of their fortes.