First thought would be Joe South with "walk a mile in my shoes."
Then this.....
There's a lot of lines in this song but here is the one that gets me every time.
Trent Reznor - Hurt
"Beneath the stains of time
The feelings disappear
You are someone else
I am still right here"
The question was sad lines from sad songs and Reznor was the writer. But if you'll notice I did note in a previous post that the best version is and probanly will be Cash's version. I also noted that, aside from being a reflection upon his life it was a gift of tragic honesty to his family and his fans. Even Reznor thought so. I'm a big fan of Maxwell's version of Kate Bush's song "This Woman's Work" as well, and in some ways I prefer it, but I felt Bush wrote it and deserved the credit.Even sadder was Cash's version. An old man reflecting on his life and preparing for his end. Maybe a generational thing?
Liam Clancy: The DutchmanI find dementia (which runs in my family) sad and absolutely terrifying.
"Since I Don't Have You."I don't have happiness and I guess, I never will ever again
When you walked out on me, in walked ol' misery
And he's been here since then
I don't have love to share and I don't have one who cares
I don't have anything, since I don't have
You, you, you, you
You, you, you you
You, you, you, you
Yooooouuuuuuuuuu
True Doo Wop lovers will understand all the yous at the end.
This is one of the GOATs of Doo Wop, sung by the Skyliners.

Liam Clancy: The Dutchman
"Sometimes she sees her unborn children in his eyes."
You can really take your pick of any line from Jason Isbell's "Elephant," but I'll go with this one:
I buried her a thousand times, given up my place in line
But I don't give a damn about that now
There's one thing that's real clear to me
No one dies with dignity
We just try to ignore the elephant somehow
We just try to ignore the elephant somehow
We just try to ignore the elephant somehow
Somehow
Somehow
The whole of Southeastern is a target rich environment for this thread. That album will stand the test of time.
"Children of Children"
I was riding on my mother's hip
She was shorter than the corn
All the years I took from her
Just by being born.
And of course.....