Trouble with self confidence/value (My short story of how I began doubting myself)

I've realized that I get intimidated by people I admire. There is a friendship I have that is slowly falling apart, or was it even a friendship at all. When we first met, they seemed so happy especially to talk but I had huge anxiety and barley could keep the conversation up. This is a new school year, and she noticed me on the first day, she waved at me to sit next to her. So I did, and also I surprisingly had great confidence and excitement to speak with them! (Her bestfriend, is someone I introduced her to, she is also in this class, and her other friend that I met last year is here too). Though I noticed she barley spoke to me, she gave bland respones and a smile at times, she is busy speaking with her friend which I understand. And so I tried to speak with the girl behind her (her other friend I met last year) but she was really passive aggressive.. and pointed out my makeup. I remember last year she ignored me when she was like 2 feet in front of me. So now, the 2nd day of school my friend ignores me, ended up talking to the dude behind me instead. I'm not sure what I'm doing wrong. Even my other good friend is leaving me on read now. Why? I really want to know what did I do so wrong. And why they pick on me a lot. I'm sorry I was quiet last year. I don't know why so many people keep leaving me. And I'm now okay with being alone but now it bothers me a bit again. But all I want to know is what did I do wrong. That's all.