Mosaic (Levitican) Law is extremely harsh (IMHO) as in (KJV) LEV 20:10 "And the man that commiteth adultery with another man's wife, even he that commiteth adultery with his neighbor's wife, the adulterer and adulteress shall SURELY BE PUT TO DEATH!"...
However, how do you explain that King David who committed adultery with the wife of Uriah and even had Uriah placed in the front ranks in battle so he would be killed was not punished by God; nor was the woman at the well in the New Testament, nor the woman caught in the very act of adultery? Perhaps Moses got the interpretation wrong?
It was customary for Israelite soldiers to divorce their wives when they went away to war, in case they were missing in action. Bathsheva was legally divorced from her husband when David took her, therefore it was not considered adultery in the criminal sense.
David was condemned by Nathan because he benefitted personally, and it said "what David did was evil in the eyes of the Lord." The son that he conceived with Bathsheva died in infancy (II Samuel 11:26)
David repented of this sin over many years.