What should the fiancée's family be told after the semen analysis results came back abnormal, despite my having undergone varicocele surgery and having sought God's guidance through Istikhara?

If your condition does not prevent intercourse, then you are not obliged to inform your fiancée, unless it does prevent it, in which case you must inform her. However, if you are able to have intercourse but are infertile, the majority of scholars believe that you are not obliged to inform her, while some, such as Ibn al-Qayyim and Ibn Uthaymeen, believe that you must inform her because it is a defect that prevents the purpose of marriage, which is procreation. Therefore, it is better to inform your fiancée of your infertility to avoid disagreement, as indicated by Imam Ahmad and Ishaq ibn Rahawayh.