Going under fast. . . Nothing helps with my depression

Hey,
I am a 48 year old married male with one graduating high school senior this year. He is planning to attend college next fall. My story is too long and evolved to get in this box for now. I have been diagnosed with recurrent moderate depression with anxiety since 1991. I have been on almost every major antidepressant known to man, including some other supplementary drugs. I was physically and verbally abused by my father, ignored by my mother. I am an only child. I have not been able to hold down any job for years (I've had 36 different jobs since 1991). I am receiving disability payments now. My wife is a school teacher, and has been for the last 23 years.

I am under the care of a psychiatrist and he is doing all he knows, and he is a sincere guy who really cares. However, on June 1, 2006, my world went upside down. My father fell in his kitchen and hit the back of his head on the hard floor. He was alone then.
He bled all over the floor. My mother came in from the grocery, noticed the blood, but he has made it back to his chair, but he had no recollection of the fall or how the blood got there. He was admitted to a local hospital via ambulance. He stayed in ICU for 6 weeks, then transferred to a rehab for 11 days, which proved to be of no value. The rehab moved him to a local skilled nursing home, then, we moved him to the State Veterans Home in our city, where he now resides in a secure wing of the building. My father cannot walk, is in a wheelchair, cannot carry on a two-way conversation, does not recognize my mother or me, refuses to eat by mouth sometimes, (he still has a stomach tube inserted from the hospital). He is delusional, hallunicates, argues with other residents, and just plain unpleasant to be around. We see him almost every other day.
Now for me, in 2004, my wife and I filed for bankruputcy due to mounting medical bills and my lack of ability to hold down any job. This has, of course, deepened my depression and hopelessness. This week last year I attempted suicide (my 4th such attempt) and was carried by ambulance to the local psy ward for 72 hours. I have been for 21 years a minister, and then a teacher; I have worked also in retail, banks, and in delivery. Now nothing seems interesting to me any longer. I am unemployed, receiving just my disabilitiy once a month. Now, I understand, my dad has brain-trauma induced Alzhemer's disease, Stage 3;
my mother has stage 1 and is worsening due to the stress concerning my father. MY QUESTION: Why continue on this third rock from the sun any longer?
Everything I have attempted has been futile. All the education I received (through an earned doctorate) has not paid off for me or my family. Any suggestions or new insights possibly?

Going under fast. . .