3months and my girlfriend seems to hate me

My girlfriend and I have been together for 3 months now. When it is just the two of us everything is fine. But when ever we are with other people it seems like she changes into a different person. She ignores me and seems depressed when I’m around. Also last week I had asked her a question about one of my friends spending time with her and she overreacted and thought that I didn’t trust her around ANY other guys. I know most of her friends are guys so that isn’t true, it makes me a little wary but it doesn’t bother me. But she ignored me everyday andwhen I asked if anything was wrong she said no. Until she finally told me what was wrong. Friday, I took her to a movie andthings were okay,no problems, just her and me. But Saturday we got into another fight and everyday sincehas been worse and worse. She gets upset over the smallest of things. But only when other people we know either get involved or witness us talking about it. We talked about it again on Tuesday and I thought we were past all it, but she is, once again, ignoring me and acting depressive around other people we know. Primarily her friends, not mine. I’m a little confused. Most of my friends and even my family have told me to break up with her, but honestly I don’t want to. If we can work past this I think things would be okay. But I want to know why she is acting this way and what do I need to do or say to get past this stage?