What do i do if im having sad problems with my friends that make me want to kill myself?

well it all started during the middle of the school year when one of my best friends i' ve known since preschool and im now in 7th grade going to 8th but i lost her she was my best friend we did alot together and i lost her she is hanging out with other people but now when she see's me she makes fun of me and it really hurts and i just dont know what to do but i have another friend that didnt want to be mine and my other friends friend anymore and when i see her she always says stuff to people so idk what to do anymore and if i say something to her back then the teacher's get in it and we get in trouble and then my old friends call me a snitch so i have new friends but there not realy supportive anymore? so help me idk what to do anymore im scared