My bestie stole my man and rubbed it in my face. Why would she rub it in my face when she saw I was upset about it?

My best friend "stole" my man (my boyfriend of 4 years.) She pretended to be my confidante about my relationship while sleeping with him behind my back and actively trying to sabotage my relationships with him and then they began dating.

Once she succeeded in turning him against me and they began dating, she rubbed it in my face by showing me their texts and sending me a long email detailing about their sex life. Why would she rub it in my face when she already knew how distraught and devastated I was about it? I was already so upset and she wanted to rub it in my face some more. Why would she actively try to do that and make me more upset?

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She also said in her email that she's gonna "make him her bitch" and that she's gonna control him and wear the pants in their relationship, and that he never loved me like he will love her. Why is she trying to hard to hurt me?
My bestie stole my man and rubbed it in my face. Why would she rub it in my face when she saw I was upset about it?
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