All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.
In fact, what your in-laws are practicing is forbidden and very dangerous. Taking money for this is yet another forbidden act. Magic is polytheism.
The Prophet forbade the utilization of the price of a dog, the earnings of a prostitute, and the earnings of a fortuneteller.
Fortune telling is magic and what you told your husband, that one should turn to Allah at times of difficulties and hardship is the right thing. In fact, it is Allah Alone Who makes a way out to difficulties, cures the sick and prevents anguish, distress and trouble. So, whoever turns to Allah and asks His Support against these magicians and witches, then Allah will help him by His Will as He is The Almighty and The All-Knower, and He will turn the magician's cunning and craftiness against the magician himself.
Hence, we advise you to recite Soorahs Al-Falaq and An-Naas [i.e. Chapters 113 and 114] along with the authentic Beautiful Names of Allah and His Attributes.
As for your breaking all ties with them, we believe that you should first advise them and call them with the best manners towards Allah, The Almighty.
In fact, mixing with them and trying to convince them to turn towards Allah is better than breaking ties with them, as Allah could guide them to the right path through your attempts as He guided your husband.
Allah knows best.