The ending

The ending was clear if you saw it all. It turned out that the Sean Young character masterminded the manipulation of the ambitious bitch character, knowing her type, into being motivated into killing her husband as well as the added advantages of ridding her of other persons she considered hindrances to her endeavors. Thus she was the grand puppet mistress of the entire event, except that she made at the end the mistake of assuming that her husband was dead due to his lack of responsiveness, whereas he actually not only wasn't dead, he was also conscious enough to hear her explain her intentions and then to kill the perpetrator as if in self defense being thus the auditory witness to her admission of guilt.