Speak from your heart
and tell him the truth, as you see it. Be prepared for excuses and denial. Be prepared for bargaining. If you and your partner have specifics, lay them out. As in...you need to be out of here in two months (or whatever you two have in mind).
You and your partner are setting boundaries. This is not usually met well by alcoholics. Do it anyway.
Good luck.
Peace,
Gabe