I need some sort of advice

Is it normal that my ex best friend still holds a grudge against me even after almost 6 months have passed since I ended terms with them? They go as far as to try to make my life shitty with their attempts going in vain. Because nothing they do can absolutely phase me.

Certainly we did end on bad terms, they were the one who talked shit and tried to set me up. But when I stood my ground they got mad and tried to go as far as to guilt trip me. I believe they are kind of stuck up tbh.

Honestly I’m kind of rattled because we go to the same school and I don’t want to ever see that face, their partner is kind of dangerous. And both of them are against me.