I think i hate my 'best friend'!!!?

Kay, so im talking bout a few girlss I met this year in grade 7. we went on a over night feildtrip yesterday and today and Stephanie pissed me off soo much. She seems like .. two faced! At first she was like the nicest person ever, but now shes such a b***** . she acts like shes everything. In our fieldtrip we were playing a game and i picked out a peice of wood and said "this is wood" and steph was like "no its not your so stupid its a rock" and it was sooo obvious it was a wood. Then she spent like the next 3 minutes discussing with hayley how dumb i am. Then we went swimming, and i straighten my hair everyday, and i didnt bring my straighter, so my hair was realllyy wavy and kind of frizzy. Stephanie brought her hairstraighter. She spent the whole swimming period showering and doing her hair. She straightened her hair and i asked if i could use it just to fix my bangs so i dont look as bad, and she said okay. I straighted like 2 peices and she came and she was like "wait i need it" and then she took and it and then unplugged it and i was like "i thought i was using it" and she was like "no." She didnt even need it. She put it in her bag and did her makeup for like 10 mins. So i had really ugly poofy hair for the next 2 days and everyone kept on telling me how awful i looked n i was about to cry. In another class, she took the seat i was sitting on, because i pulled it and she sat on it, and she just grinned. Then whne we switched, i did the same and she gave me a rude face and i grinned. On the bus stephanie was like "nice hair" sarcastically, and i watned to say that its her fault that she wouldnt let me fix it, but she probably expected id laugh and be all cheery like i always am but i was pissed off. I just look straight at her and ignored her. Then at boston pizza Stephanie and Hayley <- my other friend, barely talked to me. Then back on the bus, Hayley said she was sick of ALL of us except for stephanie, and last week she was telling me how she sometimes really hates stephanie. They seem fake!! but they are my friends so, what should i do?