It seems unlikely that the Japanese were close to surrender. There was a culture that death was preferable. I have seen film of Japanese mothers holding children jumping from cliffs on Okinawa.
The firestorm raids on Tokyo killed far more people than the atomic attacks(likewise Dresden, Hamberg Etc.), but did not break the will to fight on.
The attacks were a monstrous evil, but still a vastly less costly evil than another year of conventional warfare.
Keith.