Would this be backstabbing or betrayal?

this was a long time ago with this girl i know. i was so mad i said that i hate my highschool and i hope the whole school burns down and i sent it through a text message to my friend and she said she accidentally showed it to her mom and her mom said it and reported it to the school but nothing happened to me. but that time i graduated already. should i still be friends with her? what would u do?