You can't protect your children from it. They know Dad is this way and are expressing their disappointment. The fact is that they now feel that they have to protect you because you haven't change the situation. I'm sure it breaks their hearts to realize that their mother lives with this all the time. No child wants to watch the parent get left behind with these problems while their life moves forward.
You have a lot of decisions to make. Try to support each other. And get help for your husband.
Much Blessings
Ocean