Why does my "friend" do this?

ok.. so i have a friend and the other day on the way home i got 5 texts say i Was a B****, F*** me and other thing like that and it Was sent from my friends phone. so i deleted them cause i was mixed emotion's so today i Was staying after school with my teacher cause i needed help and i get another nasty text so i showed her and she said to show my mom and tomorrow during my study hall go down to the school consular. so i am and i show my parents. What should i do/act towards my friend????