I too could have written your thread neeps, your definately not alone.
It's a catch 22, get generally down, see things that might be changeable but not have the motivation to really pursue doing much about them, get a bit more down, see more things that could be different, get a bit more down....
I love the idea of "escaping" from the children for a few days, also might it be possible to start with some small steps, just to change the day to day, some silly, short, change of perspective ideas :
Drive to an area that is awful (lots of poverty, burnt out cars etc) - sit in car watching rubbish blow by, drive home feeling glad that you can.
Spend an afternoon sitting in the viewing gallery of your local magistrates court (criminal courts even better - the Old Bailey is fab), drive home feeling glad that you can.
Walk through your local hospital, have a coffee in the canteen, really look at the folks coming and going, drive home feeling glad that you can.