Because I have sinned against him— Because I am about to be his victim, or sacrifice for sin. Nothing is more common in the sacred Scripture, than to denote the expiation of sin by the word חטא cheit. See Houbigant.
Related Commentaries of Micah 7:9
Micah 7:9
9 I will bear the indignation of the LORD, because I have sinned against him, until he plead my cause, and execute judgment for me: he will bring me forth to the light, and I shall behold his righteousness.