How do I reconcile the fact that I am 57 years old and must begin a brand new life as if I was a 20 something straight out of university? When all of my friends and acquatances are retiring to a comfortable life, I must start out brand new with an old body and old brain. In this economy I would be competing with 20 somethings with MA's and Phd's with fresh, bright, quick to learn new brains, while I only have a BA and a middle aged brain which has been burdened so long as a caregiver? If I were an employer I wouldn't hire me either and so I don't blame them. I cannot realistically compete with the young people. I cannot fantasize that I would get a good paying job, but only one that hopefully can only pay the rent, food, toilet paper, the necessities of life, never mind any type of small luxury--like expensive ice cream like Breyers would be a luxury.
What's the difference between intelligence and wisdom? About 40 years. (You have experience and maturity the 20 somethings lack.) You may be down on yourself (I'm guessing from the "I wouldn't hire me" comment) or even depressed enough/still recovering enough that a grief group or counselor if there is anything free or affordable would be good.
Take care of yourself physically too, it will make a big difference - pick any kind of exercise you like and can do, start where you are, and go on from there...don't even worry if you can't do a 15 minute mile to start with, just check with yoru doc and see if you can get started swimming, doing Tai Chi, walking any pace, any distance if that's the case.
Let us know what you decide to be when you grow up (as my son still asks me sometimes :-), and how it all goes, OK?