I could go on all night but I have to sleep sometime. You also need to see teh historical context. You, libs in general, but I'm talking to you, try to use modern morality on last centuries problems.
When your country has lost 400,000 men & women fighting on 3 (4?) continents over a 4 year span & all you can see is more blood & loss on the horizon, the (generally) untested A-bomb looks like (and is) a lifesaver. It ended the war in 3 days, not 3 years. It saved countless lives. It was the best solution we had.