I don't want to sound critical because you are having a tough time. So I will try to lay it out softly.
First thing is set an appointment with a psychologist. Why? You seem to have some addictive characteristics to your behavior. Meaning if you keep doing something despite increasing negative consequences, you are intentionally harming yourself. Either you dont realize it, or can't stop it. But taking to something and immediately immersing to an obsessive level is a sign something may be driving you.
Secondly, take a look a look at what you get out of your high mileage and road riding persona. Whatever you get from it is more important than your health and pain free life. Whatever you are suppressing is at least as, if not more painful than the harm you are causing yourself.
Third, yes try a new bike. Flat bar road, touring, endurance etc. Something that doesn't cause you to bend your neck for so many hours. If you can't fathom riding one of those styles, refer to point 1.
Last, find a PT who rides and ask them to do a long ride or two with you. If the exercises make you feel better and riding makes it worse, there may be something around your technique which is causing the pressure and pain.
Good luck.
I bought my first (and only) road bike in August 2017. I brought my bike to college and used it as something to do in my free time and quickly fell in love with it. It gave me something to do, set some goals for my self, and I gained so much confidence from it. I do have a personality where I have a one track mind. Basically from the time I bought my bike until I injured my disc, all I thought about doing in my free time was riding. I saw 3 orthopedist to diagnose the issue. All agreed that it is ok to still ride. Keep in mind I have GREATLY decreased my mileage. In 2019 I only rode about 1600 miles. I am limiting my mileage to 20-30 miles, so I don't really feel like I'm hurting myself. Someday's my back feels worse than others. I still enjoy it but would like to go back to longer rides. I'm keeping up with PT exercises for now to accomplish that goal.