Hateful coworker?

im in the army and im an E3 and the girl i work with is an E4(i wish i could tell her off), she is always telling on me, alwayz observing everything i do like literally staring me down and no one is doing anything about it. she is always saying i have a bad attitude, i dont recall that and i've tried doing nice things for her, but she still give me attitude about everything.. i never say a thing to her. a little thing can happen in a day and she runs back and tells the world what i did and i get punished for it.. She has her own dirt too, but whatever i say doesnt even matter, but she got everyone to believe that i am a bad person or somethin or i cant do anything right.. i hate working with people in a hostile enviroment she is pregnant so am i, maybe it the pregnancy..shes nice to everyone else but hates me dont know why. it seems that i cant do anything right. whats wrong with me?