Re: when things fall apart
Personally I think you're right to feel for the whole world. The average person on this earth makes about $2 a day. That means no real nutrition, potable water, or livable shelter for them and their families. And of course half the world makes less than that with 2 billion people in some stage of starvation.
If all of us had this tugging at our souls, no matter how painful, the world would change. There really is enough for everyone. So in a way, it's all of our duties to live with conscience, guilt, and unease - as long as so many of us live such subhuman lives.
Ghandi said something to this affect. That he couldn't live in complete happiness when so many suffer.
But the suffering we CAN get rid of with a clear conscience is that which comes from clinging to illusions of permanence. And as you say, that comes from just understanding the truth and gaining perspective through physics, astronomy, Buddhism, Yoga, etc. And re-reading "When Things Fall Apart" often would go a LONG way!
However just because we suffer doesn't mean life is shit. We're made to suffer! We have miles of nerve endings to create sensations of pain. We have deep
Depression and all kinds of psychic pain. But it's all there as an alert - not a punishment.
Here's what I ask myself when I start to feel that life is nothing but meaningless random shit. Would I prefer that life never happened? That I never lived at all? If the answer is no - then I've clearly been given a gift as a living creature. One that I owe a debt of gratitude for to someone, something, or the universe at large.
And through developing your spiritual self (through yoga, meditation, Buddhist principles, philanthropy, whatever) you rely less on that which is impermanent for your happiness and therefore suffer less from it.
It's a process for sure, but one thing I don't agree with in Buddhism is that the ultimate object in life is to be free of suffering. And I don't believe the Buddha did either - but given the overwhelming amount of it (then as well as now) it was a hell of a place to start.