After 40 odd years of flying I can understand the sentiments expressed on this thread and find the level of empathy quite touching. However once locked into this business it is very hard to get out , many have tried but few succeed and then often return years later .Pilots do not make great businessmen - too naive. Ask anyone who has lost their licence how it feels to be unable to fly , and the relief when it is regained.
Flying commercially still offers reasonable remuneration , a fun day out (if you make it one) and no real problems to take home . Ignore the management messages and the doomsters on this website , live for the day. (OK 3am sucks)
So what to do ? Well start by taking 3 months out ill health, sounds like you need a break , stop drinking , get some exercise. When you return to work (with a sun tan and leadened heart at the prospect of another 20 years in the flight deck) , fill out a right to request flexible working form , obtainable from the HR dept. This assumes dependent kids under 17 , or rustle up an elderly demented relative or unwell spouse. If non of the above are readily available then no problem, you could try a "request part time" , which would eventually be granted.
Work 50% ,allowing you to look at alternative employment , at least you will have regained a degree of control of your life , which is probably the underlying issue.
For the vast majority of the workforce our jobs are from time to time boring , pointless, we are undervalued , exploited , unrecognised , the bigger the company the worse it gets .
Last of all be grateful in the current economic climate that you are still employed and as you know, I'm sure, aviation can suffer abrupt and unexpected reversals. Better to have income than a cardboard box.
Good luck!