"grim realization" is correct and usable in written English.
You can use it to describe a sobering moment of awareness with a negative connotation. For example, "When I saw the extent of the damage, I had a grim realization that this would take many hours to clean up."
No author was better at that sort of grim realization of the price of one's desires than James M. Cain.
This grim realization comes from personal experience: each has a teenage daughter who falls prey to heroin.
His is the moral voice, through which comes the grim realization that ordinary human beings become pawns to fulfill the destiny of power-mad, pseudo-messianic leaders.
Arriving on the shore, the immigrants face the grim realization that they have left behind one war only to be drafted immediately into another.
In a grim realization that predates Rachel Carson's "Silent Spring" by several centuries, that isolated set of islands in the southern Pacific Ocean lost many of its native birds to introduced mammal species, Homo sapiens among them.
Many of those who voted, as I did, for Barack Obama must have experienced a similar simultaneous sense of relief and despair last night, as jubilation gave way to the grim realization that the political paralysis of the past four years will become, if anything, worse and more bitter.
The two-hour set reached some desolate places: the bitter boogie of "Saving Grace," the grim realizations of "When a Kid Goes Bad," the weary longing of "Wildflowers," the sullen rage of "I Should Have Known It".
(One of the many grim realizations for the listener in this story comes here — recognizing the gratitude we've felt in similar moments, and knowing that for Debra it's going in a bad direction).
The grimmer realization of recent decades — a time of looming man-made cataclysms — is that we do not live in geological or astronomical time.
But when the young man's stepfather shot himself to death on Wednesday after an eight-hour standoff in Dix Hills, N.Y., the police were left with an even grimmer realization about who might have committed the murder and why.
But others, like me, will read this news with grim recognition and the sad realization: "That could have been my kid".
