I hate this girl... well i know its not good to hate people... but ....?

she came to my school this year and.... from my point of view, she stole two of my best friend and now they are so much different then before they now swear a lot and speak in other language other than english around people who can't speak the language and they rarely talk to me now... she is loud, she just stays with them and more... i dont know there are mor reasons why i dont like her but im just not sure if i am right to hate her? coz now she also hates me and ignores me but in class we have together i sit with her coz of pity... i dont know i just really dont know im solonely and i cant concentrate with any school things and i've been crying nearly everyday and i also crying myself to leep... im so confused! please help