Truman by David McCullough:
On another day Robert Oppenheimer came to see him privately, and in a state of obvious agitation said he had blood on his hands because of his work on the bomb. For Truman, it was a dreadful moment. Oppenheimer’s self-pitying, “cry-baby” attitude was abhorrent. “The blood is on my hands,” he told Oppenheimer. “Let me worry about that.” Afterward he said he hoped he would not have to see the man ever again.