As I like to say, there is absolutely nothing to be sorry about regarding Hiroshima and Nagasaki. Besides the many American deaths and injuries avoided, we literally saved millions of Japanese lives, and millions of Chinese and other occupied territories lives (Korean in particular) as well, by dropping those bombs and forcing surrender, vs. invading Japan.
Anyone who thinks otherwise is completely ignorant about the history of the era, and needs to sit down and shut up until they fix their ignorance and can discuss the issue from a position of knowledge.
Victor Davis Hanson has a couple of shorts on YouTube discussing this. He indicates that we had 2,000 additional B-29s that would have been delivered by the end of 1945, and several thousand other 4-engine bombers laying idle on airfields in England. Curtis LeMay had plans to up our bombing raids from 4 or 5 per week to 2 per day. He would have burned down every city in Japan within six months, and probably killed at least 2 million Japanese. That’s without blockading Japan from all food and energy imports, and before an invasion.
The atomic bombings were horrible - but worse could have been done, MUCH worse.