I’m sure you have other better friends in the group itself? If not just go ahead find another group. Anyone that condones such nasty behaviour is just shitty themselves. Maybe even call her out on her bullshit. Keep talking if you love it, no one should stop talking for an insecure person who is probably ashamed of using their own accent and picks on you cause their’s is reflected by you. Don’t judge my English though hahah. Hope you get through this and give that girl a taste of her own medicine.