In gentleness I can only say, you do not have the power to keep him on track.
If he chooses to drink, he will.
If he chooses not to drink, he won't
If you are feeling sad about your current situation, maybe it's time for you to make some changes. Change begins with you my friend. If You don't like a certain aspect of your life, only YOU can fix that for yourself. When we look to others for our personal inner joy, and security, we always end up with the short end of the stick.
This is no longer about him, it's about YOU. His actions and choices have worn you quite thin. ( I understand this) Perhaps you could reevaluate how you feel about him. Relationships are forever changing, it takes two mutually invested people, willing to commit and do the work together. When we involve ourselves with an addict, again we get the short end of the stick, as only one person is actually committed to the relationship, the other one is off numbing their brain.
Today, is a good day to make yourself the # 1 priority of your life.