flower......I do understand that you would like to have an amiable, cooperative and rational conversation with him about this---I can imagine that you are the type of person who operates in this way in all of your affairs. And. I also understand your sense of loyalty to him and wanting full transparency---as I imagine that comes from your ability to empathize with other people, I think that anyone who has taken their marriage seriously does feel a sense of loyalty. I consider all of these to be good qualities.
This is why I think that alcoholism is such a Monster to those of us who have loved an alcoholic or addict. In fact, there are two situations that are said to defy the usual "rules" that work in healthy relationships. Those are Addictions and Abuse. These two situations turn the regular relationship rules all topsy turvy.
He will not be able to participate like you want, due to his disease---and he will not be able to prioritize Your welfare. You are going to have to be the one to look after your welfare and ultimate well being (and sanity).
You want to hang on to the periods of "good times". Who among us have not experienced this.!? Actually, this is the critical link that keeps so many people in the cycle of abuse---in abusive relationships. This form of intermittent reinforcement can be very powerful.
As you describe it, for you---it means that you are basically "living on crumbs"---emotional crumbs.
The problem is that, with alcoholism. those crumbs will, over time, become smaller and less frequent.
As it is, the way I understand it, is that you have been drinking your emotional sustenance from a smaller and smaller cup---as you have become more isolated from others and have too few people who have your back to guide you and give practical help as you go through this. Real llfe, face to face persons to help hold your hand. I think you need more helping peeps around you. It makes all the difference.
Yiou are entitled to do whatever you need to do to take care of your own welfare. It is your right.