Some things just sneak up on you. Taking you completely unaware. You could be merrily traipsing through life with not a care in the world. Till kablamo!
A memory you thought you had forgotten trips you up. Or you learn something ugly about someone you thought you knew. Or there is some new horror that your mind has decided to unleash on you.
Momentary. Yet enough to leave you breathless and powerless.
Like a giant sucker-punch that life deals you. Right between the eyes. Leaving you with a broken and bloody nose, tears streaming down your face, completely disoriented. And all you can do is curl up into a ball, waiting for the blood and tears to dry and for the image to dissipate, so that you can go back to living.
Just one flash.
That's all it takes for everything to go to hell.
One memory, one word, one look, one moment.
Life is pretty unfair that way. Especially the sheer simplicity of it.