All I know is, I wasn't there, i.e. living in the world of 1945. Nobody else here was, either.
I was living in Hiroshima, right in the center of the city, for two years in the early 90's. Met a lot of people who lost family, even one man in a suburb town who saw the blast happen and the cloud after, from about 10 miles away. Went to the Peace Memorial Museum a couple times, participated in Aug 6 ceremonies both years I was there, basically surrounded by it 24/7.
And occasionally, I would get asked about it. Did I feel sorry? Should the US apologize? etc. And I said the same then. I wasn't there, living in the world of 1945, so I don't have an informed opinion and never will. The people who were there thought this was necessary to end the war. The behavior of Japanese soldiers in battle, the behavior of Japanese civilians on Okinawa, and the behavior of the Japanese military and government led them to believe that it was necessary. Whether they were correct, in hindsight, is a pointless question. It was done.
What I didn't say, but always felt, was, "don't start anymore wars trying to take over Asia and you'll never need to ask again."