i'm pretty sure it was done by the in-house writers and producers at Rockstar (mostly helmed by Woody Jackson, score-wise). not 100% on the credits, but i think D either wrote and sang it, or just came in and sang it. it's meant to get you right in the feels during a specific point in the game where the lead character has gone through the shit, with still more shit to come. very much a song made for the game, not somethin D had lying around in the archives.

the first RDR had a similar song and 'moment'.

(i don't play the games but i love watchin the cut-scene 'movies' gamers make of em on youtube).

V.