Are the grandmother, mother, and aunt considered unjust, and are they sinful due to the aunt's insistence on marrying a man whom the family did not approve of? And are they blameworthy because the aunt said: "I will never forgive you my whole life"?

Your maternal aunt has no right to claim that her mother and sisters wronged her and to refuse to forgive them, as no injustice was committed by them. Rather, they advised her. Furthermore, they are not her guardians to prevent her from marrying. She should strive to reform her husband, or weigh the two harms and choose the lesser of them.