Holocaust and Plague of Darkness

Rav Yaakov Kaminetsky (Emes L’Yaakov Shemos 10:22) Rashi asks, “Why did G-d bring about the plague of Darkness? Because the Jews in that generation were wicked and did not want to leave Egypt and therefore thousands died in the three days of darkness.” Even though that entire generation were not considered righteous (tzadikim) as we see the angels claimed that both the Jews and Egyptians were idolaters –why were the Egyptians killed to save the Jews. In other words the angels could not see the slightest difference between the Jews and the Egyptians and thought all should die. And thus the Jews that died were apparently killed entirely because they were preventing the other Jews from leaving Egypt because they had a tradition that the Jews must remain enslaved in Egypt for 400 years and since the time had not passed they were afraid that they would suffer the fate of the Ephraimites who left prematurely. They thus did not believe the words of Moshe and the Elders that G-d's calculation was based on the merit of their forefathers. Therefore G-d killed only those but not all the Jews even though in the eyes of the angels they were all idolaters. Only G-d was able to distinguish Jews from the Egyptians and know that the Jews would eventually be capable of accepting the Torah at Sinai. How did the Jews react to this mass death at the very time they were expecting to be redeemed? He says that this can be a source of comfort for the Holocaust in Europe that we are closer to the final Redemption