tbh, i do not know what to do if i am in your case, but if there's one thing i will do, i'll probably talk with them about how i actually feel, that i feel left out. i know it's hard and yes it feels terrible but they need to hear you out. if they are real friends then they will apologize sincerely and do something about it, but if they just keep on doing it after everything you said then you might want to try look for other friends that will give you more importance. ugh punch me pls.
its just one person. i used "they" because if i revealed his/her gender id narrow it down too much that if my irl friends see it they could guess. but youre exactly right. if this person cared enough theyd do something about it. i guess i could be a fault too.. for not confronting her enough and just thinking of her as a bad person. ugh ill never be satisfied.. but honestly, id rather be the one hurt than watch someone else get hurt. idk
im thinking too much