Please help me im so stressed out...my life is a mess!?

okay so im taking the PSATS tomorrow and im really nervous ive been doing to practice packet they gave us and its so hard in the english section i cant even pronounce most of the words and that stresses me out and then in the math...the questions would be so easy if they did not word it so much! its impossible..and im really stressed out because me and my boyfriend and in a huge fight so thats on my mind..i lost my calculator so now i have to use a sh*tty one and my mom is freaking out telling me shes worried that im not going to do well and that makes me even more nervous! i didnt get a chance to study tonight cause i had to work till ten...my sister who is in my grade is taking it too and she is soo smart..i wish i was as smart as her.. i dont want to look like an idiot when her grade is better then mine..shes doing so good in school like A's then im getting C's i just want to be as good as her...and i dont know what to do im just freaking out...FUC*K...im a junior and i really want to get good grades this year. i want to get into a good school i need help...what should i do?