What is the ruling on the husband believing the claimant of sainthood who alleges that his wife is bewitching him, and is this claimant one of God's righteous saints, given that the wife knows her husband never misses an obligatory prayer, constantly performs Hajj and Umrah, and works as a doctor in Saudi Arabia?

Your ex-husband's visit to the soothsayer and his claim that a torment will befall you is a grave error and a great sin. For the soothsayer is not a friend of Allah, but rather one of the devil's allies. And whoever comes to a soothsayer and believes him has disbelieved in what was revealed to Muhammad. If he does not believe him regarding knowledge of the unseen, but believes him concerning jinn receiving information from angels, he does not disbelieve, but he has committed a major sin. He must fear his Lord and beware of harming Muslims. And you must be patient and rely on Allah.