I have the feeling that my boyfriend's female friend dislikes me?

Hi, need to get this off my chest because everyone I know seems to take the issue lightly. I'm 21 and I have a wonderful boyfriend, it's the first relationship for both of us. We started dating since last November and the year has been a delightful succession of happy moments: he's sweet, intelligent, caring. The problem is his friend group. Or better to say, one female friend of his who's part of the aforesaid group. Yes, I have the feeling she doesn't like me.
I know her since middle school, and she always gave me those mean girl vibes. She used to make fun of me and another friend of mine; she has always disliked me without reason. However, since she's part of my boyfriend's company I decided to put past hostilities aside since she looked more mature, although she always kept that attitude I couldn't stand (intrusiveness, attention seeking, etc). Things seemed to be going well between us: I really thought she became the best version of herself as she spontaneously approached me once and has been nice and kind, but a friend of mine recently told me that she talked shit about me at an event, and I feel sick and demotivated at this point. I vented with my boyfriend, he was pissed off and assured me he would talk to her. Why is she like this, and what do I need to do? I need your opinions.
I have the feeling that my boyfriend's female friend dislikes me?
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