Little Mother(1973)

Marina Pinares, the wife of the president of a South American country, insists on being his vice-presidential running mate in the next election. She's no stranger to assassination to get what she wants, so some suspect she'll kill her own husband after the election to become president. In a series of flashbacks we see her rise to power: a party girl willing to sacrifice a friend's virtue to gain favor; the lover of a soldier she later tortures; the mistress of the military man she soon marries.