Who is the spider woman?

Manuel Puig’s 1976 novel Kiss of the Spider Woman is, on the surface, the story of an unlikely friendship that develops between the two protagonists: Molina, a homosexual imprisoned, officially, for the crime of corrupting a minor, and Valentin, a communist revolutionary opposed to the repressive military regimes that rule Argentina. The two share a prison cell and initially have nothing in common. The circumstances of their situation, however, force them to enter into a dialogue that includes protracted recitations by Molina—who is a film-buff loosely modeled on the story's author—of the plots of movies he has seen. It is a way of killing time while they both hope to retain a measure of sanity. Molina’s descriptions of the films and Valentin’s questions and comments enable the two prisoners to engage their imaginations by debating the details and idiosyncrasies of the characters.
In Puig’s novel, the spider serves as a metaphor for betrayal. Molina and Valentin’s dialogues during the former’s recitations of film plots invariably focus on women. Molina, it is revealed in the novel, has been deliberately placed in Valentin’s cell by prison officials for the purpose of spying on the political prisoner/revolutionary. Late in the novel, the two prisoners consummate their relationship, at Molina’s urging, despite Valentin’s heterosexual inclinations and strong interest in women. The betrayer, Molina, has been informing on his friend and, now, lover. As Molina prepares to leave prison, he asks Valentin to share a kiss before he leaves, prompting Valentin to say to him "You, you’re the spider woman, that traps men in her web." Female spiders, particularly the black widow, are known for killing their male mates following procreative intercourse. The spider, then, is a metaphor for Molina’s potentially deadly betrayal of the "male" in their relationship. The irony in the novel’s conclusion, therefore, resides in Molina’s murder by Valentin's comrades.
The "spider woman" in Kiss of the Spider Woman refers to the character of Molina's enticement of Valentin into a sexual relationship, knowing that he has been spying on his friend for a regime that represses homosexuals. The complexity and darkness inherent in relationships is a theme that underscores much of Puig’s novel, with Molina’s description of the film Cat People providing a context for the two character’s discussions. Deceit and betrayal are the common characteristics at the heart of many of these discussions, and the metaphor of the female spider is the story’s most potent symbolism.