God is not in disagreement with Himself about while laws we should follow, but rather the Law of Christ is the same as the Law of the Spirit and the Law of the Father, which was given to Moses. Jesus set a sinless example of how to walk in obedience to the Mosaic Law and did not hypocritically preach something other than what he practiced, so it wouldn't make sense to think that the Law of Christ was something other than what he taught by word and by example. In Psalms 119:29, David wanted God to be gracious to him by teaching him to obey His law, so that is how Jesus showed his grace to us, and it is contradictory to preach grace and the Law of Christ while preaching against keeping the Mosaic Law. In Jeremiah 31:33, the New Covenant still involves following God's eternal law.
Jesus was one of countless people who fulfilled the law by teaching how to correct obey it by word and by example. All of God's righteous laws are eternal (Psalms 119:160), not just ten of them. In Deuteronomy 4:2, it is a sin to add to or subtract from the Mosaic Law, and Jesus was sinless, therefore he did not do that. The command not to look at a woman with lust in our hearts is just the correct application of the 7th and 10th Commandments against adultery and against coveting in our hearts, not something brand new.