Bummer Bob
You have a such a damn good attitude. I feel like you can make progress if there's progress to make.
I think there's 3 things you need to do:
(1) Do you feel like your identity is as a distance runner? Could you leave running (for a while) and be emotionally healthy? Or are you narrow in your focus? Is running an obsession or compulsion?
(2) Do you enjoy running? Sounds simple, but is it sometimes a pain to get out the door and run miles? Do you get anxiety trying to cram runs into your schedule?
(3) Have you looked at this from all the angles? If I was you, I'd concisely and coherently approach a different coach or experienced runner who helps runners train and explain your situation and ask for help. Is your current coach adjusting your workload to fit your talents/thresholds/etc? You may need something specific...or someone else all-together
Long story short: i was a 25-30 mile per week guy in high school and got bumped to 70-80 in college and it crushed me. I told my coach i needed less miles or i couldn't do it. he was awesome and agreed to try. one day i was in a fast heat of a race and i realized there was a 3:58 miler in my race. I was almost 19 and he was a 22 year-old man. I ran the fastest mile of my life, had a great week of practice and quit college running. it was so hard leaving all those teammates and friends but my life got so much better. i didn't run for 5 years after that.
now, 12 years later, i race all the time. i run my 30-40 miles a week on my terms and love running. I am competitive and realize how important running has been in my life, and how important not having it in my life for a while was as well.