What do you get out of this relationship now?. If you do not trust him and are fed up with his lying then I have to ask you why you are still there. You cannot protect yourself fully from the realities of his alcoholism let alone your children (who are hearing and seeing far more than you care to realise as well).
Do you think he is driving under the influence as well?. Its not beyond the realms of possibility here. He could also go onto lose everything and everyone around him and he could still choose to drink afterwards. There are no guarantees here. The 3cs re alcoholism are indeed prescient; you did not cause this, you cannot control this and you cannot cure this.
Stating that you do not want to split up over this (been together over 12 years) sounds like the sunken costs fallacy and that causes people to keep on making poor relationship decisions. The idea of sunk cost states that an investment of money, time or energy must not necessarily influence your continued investment of money, time or energy. The past investment is “sunk” into the endeavour and cannot be recouped. It is gone. Ongoing investment will not resuscitate what is gone when the investment is a bad one.
People get bogged down by focusing on their sunk costs.
There are two ways to understand this process, both involving avoidance. One is an avoidance of disappointment or loss when something doesn’t work out. When a relationship doesn’t succeed, especially after a long period, especially after many shared experiences and especially after developing a hope that the relationship would be a good one, it is a loss. It is a loss of what might have been and an acknowledgement that a part of one’s life has been devoted to this endeavour.
Another angle to evaluate is that focus on “sunk cost” creates a distraction from one’s inner truth. The sentence often goes like, “I’ve already invested to much, so I can’t notice my thoughts and feelings that are telling me to end or change this relationship.” This is a type of insidious defense against noticing yourself. You enter into a neglectful relationship with yourself which divorces you from your inner thoughts and the quiet feelings that might guide you in your life. In other words, thinking about what already has been may prevent you from deciding what you want your life to be.
Would you describe him as an alcoholic?. Like many alcoholics he is in denial to the extent of the problem.
What do you want to teach your children about relationships and what are they learning here? They really do not warrant having an alcoholic dad in their day to day lives; it will mess with their heads big time and could well leave them with a whole raft of emotional problems as adults (being super responsible, picking alcoholics as partners themselves, mired in codependency themselves).
The only one who can help your husband here re his alcoholism is him. Not you (you are too close to the situation to be of any real use to him, not that he wants your help anyway) not his parents, not his employers, nor his GP nor anyone else. Familial coercion does not work. This also cannot be solved between the two of you; he is not your responsibility when all is said and done although you likely feel very responsible for him. He cannot and should not make you responsible for his drinking.
You seem to be playing out the usual roles here associated with such spouses; namely those of provoker, enabler and co-dependent. Such relationships like you describe often have co-dependency in them too.
You need to get off the merry go around that is alcoholism before you and your children get completely dragged down by him. Your own recovery from his alcoholism will only properly start once you are separated from him.