The pilot had no regrets because he was not a sissified, fem-boy.
Unlike the guys in OMD, who did that dreadful song.
The Catholic bishop who had blessed the bombing later repented greatly, though. Nagasaki happened to be the most Catholic city in Japan.
And then of course there was Eatherly.
Carlos Hathcock, famed sniper during Vietnam was asked about if it kept him up at night being so personally involved in killing people.
He said something like “No - not with the ones I killed. But the ones that I didn’t kill keep me up. How many of my brothers did they go on to injure or kill because I didn’t kill them?”