Whats that anime with vampires?

in this one there are two vampires one is in love and married to this woman who becomes pregnant apparently the baby will destroy the world so the husband seeks to destroy her because he has compassion for humanity the other vampire is protecting her cause he hate man and he has tentacles the end of the movie is there is this human guy who has to decide kill the vampire about to kill her or kill her and save humanity he chooses save her because he is wearing a necklace that her husband use to wear so she mistakes him for husband ?