What do you do if you tell a friend a secret and they tell somone eles and it gets you in huge trouble?

i told my friend i didn't like this girl going out with this guy, because i kinda like him but i also don't like the girl,so i told my friend and she comforted me i was happy and joyed that she listened but when i got to school the next day no one was talking to me, then th girl pinned me up against a locker and yell b**** you think you have a chance with him i got scared and i was shaking, then i yelled no and ran, people keep telling me shes gonna kick my *** i got so scared i had a asthma attack and had to go home.... after school i got A lott of texts saying that if didn't stop talking bad about her they would tell principle...., i have 11 to 10 days of school left don't know what to do she wantss to beat me up!! help!