Fake friendships 😩

Okay so I'm been friends with this girl for 3 years and she never invites me to go anywhere but she asks the rest of my friends I feel really left out my best friends are friends with her too so it's really awkward when she invites them out but now people r telling me that she keeps talking about me what shall I belive me friends that I am close to or her ? What would u do? Also she always gives me dirty looks when she sees me and she walks up to me and starts talking to me nice because me and my friends are quite popular in school now there popular and everyone knows them they think that I'm not good enough for their friendship group I just wish I was good enough.have u ever had this with ur friends or is it just me ? I acc feel really angry with myself because when she was going through a hard time I was the only person to stick up for her and help her get through it but I just feel like she keeps using me sometimes I just feel lonely and at school I have to walk round on my own I just feel really uncomfortable and if I make new friends they become friends with them and turn them against me 😩I wish I was good enough ? This happened to me before in my old school people used to us me and pretend to be my friend just so I give them my lunch when they don't have any and I give them money when they have none but now im going to have to make new friends and enjoy myself at school people make things up about me and post things about me (aimed to me ) on instagram and Facebook it really gets me angry because they can't say it to my face sometimes I get really angry and feel like hitting them all because they rub that people love them in my face 😏😭💓why am I not good enough 😟sometime I feel like I'm not good enough and I shouldn't even be in this world but the only thing that keeps me going is my mom and sisters they support me thru all of my life