Hi JMH, welcome to the forum, so sorry for your need to be here.
My problem is I fear he is going to die with his lifestyle and I feel so helpless.
You are not alone in feeling this way. Many of us here have been through the ringer with our d cs and at one time or another ride an emotional roller coaster. If you want, you can start a thread and post about your situation. This way, folks can share with you and reply to your specific challenge.
It is a hard journey we are all on, and many of us have been there, done that. We support and encourage one another. You have landed in a soft place, post more when you feel like it, it helps to share with folks who understand.
Hugs for your hurting heart.
leafy