A person who betrays a trust, especially by speaking negatively about someone behind their back.

धीरे-धीरे धोखा देने वाला व्यक्ति

English Usage: She thought he was her friend, but he turned out to be a backstabber who talked badly about her to their colleagues.

Hindi Usage: उसे लगा कि वह उसका दोस्त है, लेकिन वह एक धोखा देने वाला निकला जिसने अपनी सहकर्मियों के सामने उसके बारे में बुरा कहा।