Комментарий к Берешит 45:3

נבהלו מפניו [FOR] THEY WERE AMAZED AT HIS PRESENCE — out of shame.

העוד אבי חי?, “how could he have survived so many years of worry over my fate?”

ויאמר, After Joseph had finished weeping he told his brothers אני יוסף.

העוד אבי חי?, “is my father still alive?” Even though he had asked them the same question already in 43,27 and the brothers had answered in the affirmative, his question now concerned the state of his health, not the mere fact that Yaakov was still alive. The word חי therefore has to be equated with בריא, healthy. It is also possible that he did not really ask this question in order to receive additional information, but merely to have an opening to speak to the brothers, instead of as until now, about “your father,” but about “my father,” i.e. their common father. This was a ploy to establish close personal contact with his brothers.

העוד אבי חי, lebt mein Vater wirklich noch?

ולא יכלו אחיו לענות אותו, “and his brothers were unable to answer him;” Rabbi Joseph Kara, explains this line as follows: the brothers on the one hand believed him when he said that his name was Joseph; however they could not believe that he was the Joseph whom they had sold into slavery, and that in the interval he had risen to such an exalted position, ruler over mighty Egypt. (Compare how Joseph is described in Psalms 105,17-18)

כי נבהלו מפניו, “for they were frightened of him.” They were afraid of what he might do to them as reprisals for what they had done to him.

They were dumbfounded, remembering that they had sold him and now being utterly ashamed, unable to face him.