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, sallallaahu ‘alayhi wa sallam, is His slave and Messenger.
We had previously answered a similar question of yours and we clarified to you that your husband is not obliged to obey his father in preventing him to bring you over if he (his father) does not have a sound reason for doing so, because obedience to parents does not consist in absolute obedience. Please refer to Fatwa 272152.
Hence, you are not sinful for having your husband bring you over contrary to the wish of his father. The health condition that you are suffering may be just a test, so you should be patient and supplicate Allaah to make you sound of all evil and harm. For more benefit, please refer to Fatwa 83577. Also, you are not obliged to return the airfare that your husband has spent to bring you over.
Your father-in-law has no right to cause his son trouble by preventing him from bringing his wife over. It is the husband’s right for his wife to live where he lives in order for him to preserve his chastity and the chastity of his wife, as well as to take care of his children.
The wife is not obliged to obey her father-in-law, but if she obeys him in what is lawful then this is good. By doing so, she will earn his pleasure and her marriage will be stronger; this is also evidence of her good moral character.
Allaah Knows best.