What should be done about a female relative who caused a son's divorce after only one day of marriage, and how can this be avoided from recurring despite reading the Ruqyah Shariah?

You erred by allowing this woman to enter. Whoever was known to be afflicted with the evil eye, the Imam would imprison him and provide for his expenses until death, to avert his evil and harm. This is undoubtedly the correct approach. As for ruqyah (Islamic exorcism), it is effective by Allah's permission, but its effect may be hindered by the absence of conditions and the presence of impediments. If healing does not occur, it is either due to the weak influence of the reciter, or the lack of receptiveness of the one being recited upon, or the presence of a strong impediment.