Would you have used the nuclear bomb in 1945?

Definitely.  There were no other options that would have been any better for anyone.

From the American point of view, using the atomic bomb made sense.  The number of Americans who would have died in an invasion of Japan would most likely have been huge (judging from how many Americans died taking relatively small islands like Saipan, Iwo Jima and Okinawa).

But even from the point of view of Japanese civilians, it's hard to imagine what would have been more humane.  They would have suffered horribly from more conventional bombings and then from an invasion of their home islands.

So the atomic bomb was horrible for the people of Hiroshima and Nagasaki, but it was better for the rest of Japan and for the US, in my view.