1)
What is the meaning of "Ach b'Mishpat"?
1.
Rashi, Targum Yonasan: The afflictions should be with justice.
2.
Rashi citing Targum Yonasan: With a weakened Din.
3.
Radak citing R. Yonah: The Navi speaks as if he is Yisrael, in the singular, for the Klal. Seeing Nebuchadnetzar coming to Eretz Yehudah to make total desolation, he said, I know that the affliction You put on us is good, that You chastise us - but it should be b'Mishpat, according to what we can bear. The same applies to "v'Yisarticha la'Mishpat" (30:11).
4.
Malbim: Since You want to afflict us for our sin, the affliction should be according to Mishpat, based on the level of sin.
2)
What would happen if Hashem would afflict with anger?