Who Is The Necklace Antagonist?

Guy de Maupassant's short story 'The Necklace' is about a female who wastes her life away over something that was once not even real. Despite being a protagonist in the story, Mathilde Loisel is apparently an antagonist at the same time. She is selfish and greedy woman, instantly dissatisfied with her life, which causes her downfall in the end.
Despite being born into a clerk's family, Madame Mathilde always regarded herself as an aristocrat in the novel. Through the text, 'She daydreams for luxuries, borrow necklace to wear at the ball, loses the necklace and lose her youth, her grace, elegance and beauty after working ten years to pay of the debt.' madame Mathilde's selfish personality was revealed. She fantasizes about luxury, borrows a necklace to wear to the ball, loses the necklace, and, as a result, loses her youth, grace, elegance, and beauty after 10 years of debt repayment. Which caused her to be dissatisfied with what she had and to struggle and lose her youth in the process. Despite the fact that her husband was a lowly clerk, he was able to obtain an invitation to the ball given by the Ministry of Education. His wife, however, stated that “only I haven’t a dress and so I can't go to this party. Give your invitation to some friend of whose wife will be turned out better than I shall.” which actually states that she is embarrassed through her social class and background. Whereas contrary in fact she is nothing but a clerk’s wife. So, out of greed and lust for what she didn't have, she had to live her life in misery and debt.
The necklace itself can be portrayed as a symbol of deception. To clarify, Matilda knows Madame Forestier is rich and believes all Madame Forester stuff will be expensive. However, it is not until the end of the story that Matilda learns that the necklace was a fake and she spent ten precious years of her youth working to pay off the debt she incurred after losing the necklace. In this case Madame Forestier’s dishonesty plays its role in Mathilde’s downfall.
The two ladies are at last bamboozled by appearances and want a higher social class. Madame Forestier doesn't disclose to Mathilde that the precious stones are phony, and Mathilde doesn't tell Madame Forestier that she has supplanted the accessory. The way that neither of them came clean with one another as companions, shows them to play antagonistic roles in the Necklace.