What way I could act mature I'm 23 years old and sometimes I like little kids shows that is normal?

but how can I acted my age without yelling and screaming it's just when this girl wouldn't give me space I yell and scream but when I do that then she doesn't listen she I know I already said this but when I speak up she changes the subject she won't let me do anything that I want to do and she thinks that I'm 100 pr sent shy I'm one of those half shy and half not I could be annoying but she wouldn't let me talk she doesn't like annoying people and she is. I can't talk about her tell staff tell my mom and dad I did that ten million times but they don't care and they won't do anything about it theirs nothing no one can't do anything she thinks I'm a baby and she is and when I hit her she'll hit me back anyways she hit one of my friend and my friend hit her back and she told staff on her and she ending up going to the mental hospital I don't want to go their what should I do? I just want to be friendly and nice to her but when ever I do that then she thinks we're friends and in the first place we not and when ever I scream she comes closer to me and she thinks she's better than me when ever she doesn't do like call me alot the staff says she hasn't called you in a while and they give me crap she hasn't done this or that but when ever I hadn't do anything in a while like tell staff they think that she's miss little angle but not they also say she won't do that and she would I know she hasn't done nothing to me but it's still on my mind about she got her way out of it no one believes me or understands me how should I get them to believe me and understand me?