Several posters have suggested that the OP should state what she needs from her husband.
As others have said, she shouldn't have to. However, even if she were to tell him what she expects from him, I doubt that he'd step up.
My experience of being let down doesn't relate to my husband, but to his adult children. When I had what appeared to be a serious medical problem, I phoned his daughter in order to state that he would need care if anything happened to me. (I'm realistic. I didn't expect them to offer him a home with them; I knew that it would be a care home.)
To my astonishment, I was asked "You're not thinking of leaving him, are you?"
I again stated what the situation was and gave her the number of the emergency line for the local Social Work department.
When I got the all clear, I phoned again to pass that on but also to reiterate that care would need to be put in place for DH if anything did happen to me. The response was: "But you're all right, aren't you?"
If someone is being intentionally useless, you can spell things out as much as you like - it will make not one whit of difference.