What was the discussion when you both first found out? Didn't he come up with a course of action of what he wanted you to do back then?
The disease takes over a person. We often have to differentiate between the person and the disease. Dad made plans before he had to. He made a living will. When he found out, he put my oldest brother in charge of making decisions for him when he was no longer able to do it for himself. I'm the one stuck with when to pull the plug, if it comes to that. That plan is still in effect despite the disease now spreading at such a rate, he's beyond knowing what's good for him or why my brother does what he does. (Why do you have my car? I want my car back. I'm doing great. What cops?)
I'm assuming your husband wanted you to help him. Taking care of him as long as you can, now means not listening to the disease. Listen to what he said when you knew it was him saying it. It's not easy, but you know you're doing the right thing for him, so, yes, you are submitting.