Old friends trying to be friends again!!

Why do old friends keep trying to be your friend again? Can't old friends get the hint that you don't want to be friends again. I mean you and your old friend being really close and doing things together an then they stab you in the back for a stupid reason. An when they stab you in the back and don't get the hint that you don't care so they try to get everyone else to not be your friend anymore. This is how my last year in high school was in 2009. I met this girl and became friends with her and she gets pissed over something stupid so she tells my other best friend who i was friends with for 5 years that i am saying shit behind her back so she quit being my friend also. An they both just kept trying to get me pissed because they knew if i hit either one of them that i wasn't going to get to graduate on time and they knew that i would be going to jail bc i was over 18 n they wasn't. An now they both keep trying to be my friend and i won't be their friend bc i don't like people who stab me in the back over stupid shit. I just wish they both would get the hint. Im so sick of them bothering me. People who stab you in the back doesn't deserve a second chance.