So why are people accussing me?

okk so i was meant to sing yesturday morning infront of my school. but i had gotten sick with the cold so i couldnt do it. yes it was a big event. and i had gone out the previous saturday becasue i was celebrating my birthday and it was really cold and i got it from then. my throat wasnt really 100% the day before my performace. and i went to school that day to try to sing. i did do it. but the next day when the actual performance was on i got worse i couldnt sing. people are now writing on my facebook (only some) saying ' you bludger, you wernt sick you just had stage fright, get better ay' and other people saying ' your wernt sick the day before'. how can people accuse me or not believe me. **** happens like this. soo whyy ? my music teacher is the biggest ***** on the planet. my mum called her up and i dont think she believed my mum when she sed i was sick. she is the most bitchiest lady ever. she's always treated me like crap. what should i say to the ppl on facebook and when i see them. if they start telling me all this stuff? by the way i hate my school likee i hate it soo much. i havent been really happy. im abit down all the timee when im at school. and the problem is im in the middle of my final year. and i cant do anything. soo if anyone could give me advice on what i can do to calm my self down and ignore what everyone says that would bee grea. coz i need to chill out. its been a very stressful year for me with a lot of issues with friends aswell.