Praise be to Allah the Lord of the Worlds.
If that is the case, then this divorce is invalid in light of Islamic Law and she is still his lawful wife. We advise this man to visit the nearest ftaa` office, issue her a divorce and notify her about that. This is out of kindness to her and so that she becomes lawful to another man after she observes her Iddah. And Allah The Almighty Knows Best.