The phrase "agonizing thing" is correct and usable in written English.
It can be used to describe something that causes extreme pain or distress, either physically or emotionally.
Example: "The loss of her beloved pet was the most agonizing thing she had ever experienced."
Alternatives: "excruciating matter" or "torturous situation".
It is the most painful, agonizing thing I could imagine".
"It's really kind of an agonizing thing to think about right now," he said.
This is an agonizing thing to realize, and I include myself in that as well (the candidate I liked best and wanted to vote for has dropped out of the race, so I'm left deciding between Clinton and Obama).
For Jewish college students in search of familiarity and friendship, this is an agonizing and nearly impossible thing to do, whatever their political preferences.
There are seven games remaining, which, for that cynical segment of the Jets' fan base, means that there are seven agonizing ways to lose, seven different things that could surface to spoil this promising season.
This creature enters late in the game with some blather that recalls, though with less poetry, some words of the replicant played by Rutger Hauer in "Blade Runner," who offers the agonizing admission, "I've done questionable things".
The difference is that the novelist makes things so much more immediate, more agonizing, than real-world accounts that we glance at and move on.
He's the kind of guy — we've all known Terry — who isn't stupid or malicious but just can't put things together for himself, and Ruffalo's agonizing confusions break your heart every time.
Let's go through the agonizing, but by now all too familiar, checklist of things that are terribly wrong with how his death has been treated.
He reflected on what happened minutes before in the agonizing final moments of the tribes exercise: "It was a personal thing between the two women.
Most people only read it and say it over and over, an agonizing process - but there are other ways to memorize things.
