Some Basic Arithmetic for Dying

I'm a fan of the short stories of W. Somerset Maugham. It's been a long time since I've read them, but I recall one story in particular that I've been thinking about a lot lately, It's a story about a guy who quits his job, cashes in all his assets, and heads to the South Pacific. He calculates that with the cash he's accumulated he can live for three (or something) years, and when the money runs out he plans to swim out into the ocean and kill himself.

Of course when the money runs out he finds he can't do it. The story ends with him begging on the streets of some island village.

I forget the reasons behind the character's choices, but the calculations are becoming all too familiar. Here's the challenge: Calculate the appropriate day to give up my career given the following conditions:

a) As long as I work my income continues but as soon as I quit it stops. This, moreover, is a one-time decision. There's no going back if the money starts running out.

b) As long as I work I have life insurance with a value equal to one year's salary. Moreover, if I can get a doctor's certification that I have less than two years to live the insurance policy will pay up to 80% of the policy value while I'm still alive.

c) The cost of medical care is currently in the ballpark of $5,000 a month, and this number will likely only increase as my condition gets worse. Medical insurance covers most of this cost, but my medical insurance as a function of my job. Once I quit, I can continue the insurance coverage via COBRA by paying the premiums yourself but that option expires after eighteen months. 

d) I have money in my condo and retirement accounts -- both of which are hard to get at -- and a little bit of savings.

e) At some point the cancer will progress to the point that not only will I not be able to do my job, but I won't be able to do much of anything else either. 

So when should I pull the trigger on my career?

It would actually be a simple calculation if I knew exactly how long I had left to live, but not knowing that important variable is making it almost impossible for me to figure this out. 

The last thing I want is to wind up like the guy in the Maugham story, having burnt through all my resources only to find that I still have a long time left to live.

And having to think about all this is depressing the hell out of me.