First of, I'm so sorry for the loss of your husband. My heart and prayers go out to you.
But he used a metaphor: you have to let go of the cocoon before it can become a butterfly. Yeah, I thought, but sometimes you let go of the cocoon and it just dies.
But maybe death in this case was your husband's butterfly? I know that could be hard to understand, but as you said (quoted below), he was having a hard time fighting the disease.
The disease was just so much stronger than he was. I know he didn't want to die, but he didn't want to live like that either, and he just couldn't find the enormous courage it would take to head down a new path.
Please know that you did nothing wrong. Telling yourself that "maybe I should have held on longer" is going to set yourself up for alot of guilt. Please don't do that. You did all that you could by taking care of you, and being supportive.
Please keep reaching out to others, we are all here to listen and help.
Love,
Shannon