DIilema with friends,Please help.

Okay ,i have this friend we will call her A and i knew her since yr 7.We werent close back then but at the beginning of year 8 me and her were besties.She was an amazing friend.Over time,we had a friendship group forming with 9 member and in yr 8 i fell out with one causing everyone to go on the other girls side.Which made me lose all of them except one she was therefore me and told me i can hang with her.Thinking,it will be me and her only but turns out girl A and another girl was there.I sat down next to girl A thinking every thing was good between us.But i was wrong.She kept bringing up and blaming me for everthing .I got and left and in the end i was alone.Fast foward,we sorted it and we are all frinds and girls A is annoying me to the point where she will copy my answers in test nit caring about the teacher realising,embarssing me and shaming me and every time i see i keep imagine all the **** stuff she did to me