@sunnygardens
Me again.

I just read about a relatively new "profession" that may be helpful. Aging Life Care Professionals. Your friend needs a plan for the future and that future cannot be you taking care of everything starting now, through his denial period, and on through the undeniable period.

You might end up needing to force the issue by making plans for your physical separation and then use someone like these folks to help him move forward.
https://www.aginglifecare.org/