Whether or not he is sneaking drinking, or whether or not you have an exact count of the number of units of alcohol he consumes, doesn't make a lick of difference. His drinking is all on his side of the street. He's an adult doing exactly what he wants to do.
So what do you want? I mean you cannot change him nor even expect him to change. He is not unique in any way, he sounds like any alcoholic in behavior. So even if all he ever does is binge on weekends for the next 20 years, what do you want out of your love life? You are a free human being. You can leave him to his chosen lifestyle and pursue your own!
Peace,
B.