I know a muslim sister who is a practicing muslim and is divorced from her husband. Her husband is a very highly educated man and but for some reason he is causing so much problems for her and her and this having a direct effect on the children. He is using people to spy on her just to make her paranoid and cause distress. He also pays people to make Sihr or black magic and Jinns to make her and the children's lives miserable for no reason. The women thinks it's because she is a strict practcing muslim and some people from her ex-husband's family are not happy with this and want to force her to change her from being strict muslim to a muslim with a distorted opinion about Islam. They want to force her to become a less practcing Muslim and they say that she is Mental because she is practicing muslim. She has been living in this problem for more than 20 years and nobody from the Law wants to help her. Her ex-husband is extremely wealthy and powerful man an has the Law on his side here in Britain. She feels weak against him and he knows that she can't do anything to stop him; only Allah {SW} has power over him and the people he uses against her. The mother wants to form a plan to humiliate her ex-husband and all the people he is using on television and sometimes she even wants to use black magic on them so they can feel they same problems they are causing her with black magic to teach them a lesson but she thinks that this haram. She is stuck and does not know what to do. The people that her ex-husband uses all claim to be good muslims but Allah {SW} knows that they are complete liars and Kufar because they use islam as a cover infront of other people so that nobody believes this women when she complains. Her ex-husband sectioned her under the mental health hospital and forced her to belive he is mental because of her strict islamic practicing and because she refuses to compromise her Deen. What is she suppossed to do.

All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger.

If what you mentioned in the question about that man is confirmed that he tries to harm that woman and her children, then he is very wrong. Therefore, that man should be advised and reminded of Allaah.

As far as that woman is concerned, she should be patient. With regard to divulging her husband and those who help him, then it is permissible for her to do so if this is for repelling injustice from her; Allaah Says (what means): {Allaah does not like that the evil should be uttered in public except by him who has been wronged.}[Quran 4:148]

However, she should be aware that this may have bad consequences on her, as he might seek to avenge her and the like.

Instead of doing so, we advise her to seek the help of some righteous and rational people from her family and his, or approach those who are running Islamic centres to help her in solving this problem. She may also endeavour to seek a means that will enable her to travel to one of the Muslim countries and reside there with her children in order to be safe from the evil of that man.

Moreover, she is not permitted to go to magicians in any case, because going to magicians is absolutely forbidden and she already knows this as you mentioned in the question, so how could she do what she already knows  that it is forbidden; for more benefit, please refer to Fatwa 218.

We advise her to protect herself and her children with the mention of Allaah and performing Ruqyah so that they will not be affected with magic. However, if we presume that they are affected with magic, then they should treat themselves with Ruqyah.

For more benefit, please refer to Fataawa 84498 and 82918. Also, for more benefit on the seriousness of declaring Muslims as non-Muslims, please refer to Fataawa 91567 and 84943.

Allaah Knows best.