Jerusalem's sins were serious and required judgment. But judgment was not God's final word on Jerusalem. She had broken God's covenant in many ways. Because of this, she deserved the penalty of death.
But judgment was not God’s final word. The Lord would remember the covenant he made with her at the beginning. His plans for his people could not be stopped, even by their sin. His covenant commitment lasts forever (Psalm 136).
In the end, God would forgive her sins. His forgiveness would lead Jerusalem to repentance.