"But I think to him they were all my sons."Who says these words to whom and on what occasion?What does this sentence tell us about the speaker before andafter this moment?Why does the speaker place so much emphasis on `sons'?

This quotes comes when Joe Keller finally begins to accept the repercussions of his crime/negligence so many years before. He finally understands that all of the boys who died in those planes were his sons. Keller is speaking to his wife.

Why does this realization make the ending inevitable?