Who are your lovers?
Radak: Ashur and Egypt, that you used to go to them for help.
Why do they not seek you?
Radak: It is because I struck you with an enemy's blow. I.e. I put you in the hand of "ha'Goy ha'Mar veha'Nimhar" (Chabakuk 1:6), the cruel Bavliyim. [Your lovers] could not help you, for they could not save themselves from Nebuchadnetzar.
Radak citing his father: This goes with the parable of the illness. The way of people is that friends of the Choleh come to visit him, but when they see that his illness is severe and he is about to die, his bad lovers despair from him and do not visit him or seek him. You - all your lovers forgot you, both bad and good. They judged your illness for death, for I struck you with an enemy's blow.
Malbim: Even when they come to visit you, they do not ask if your illness lightened, for you appear like a Choleh without hope to live.
What is "Makas Oyev"?
Malbim: An enemy kills, and does not chastise with afflictions. If he is cruel, he increases to afflict the victim with harsh afflictions. I struck you with an enemy's blow, a lethal blow, and also great afflictions.
What is "Musar Achzari"?
Rashi: It is cruel afflictions; the chastising is cruel.
Radak: It is Musar of an evil person who strikes and hits cruelly. "Musar" is Samuch to Achzari, for it has a Patach (under the Samech) 1 .
If it were not Samuch, it would have a Kamatz, like in Mishlei 1:2. (PF)
Why does it say both "Rov Avonech" and "Atzmu Chatosayich"?
Malbim: Your sins are great in quantity and awesome in quality (severity).
