How to proceed against an act of cruelty by wife

Wife of one of my subordinate,in his 50s, having children above 18 yrs, have attempted to abandon her husband and move along with a younger man. The woman and the third party approached the police station and reported that she wants to leave the husband and live with the third party. In the process she had alleged that husband does not treat her well. But their children, the brother of the wife, neighbors all vouch for a good conduct of the husband and outgoing nature of the wife. Now the husband wants to proceed legally against this unacceptable conduct.