why did i do that

so last year my best friend from like forever, we go way back, and we were always inseparable in grade school. she was kinda like my big sister, even though she was only a year older than me. but then in middle school, things started to change. it got really competitive with everyone trying to fit in and stuff. i felt pressure to be cool or whatever, so i started hanging out more with this other kid who is super popular but also super mean and kind of an asshole deep down. i remember one day she tried talking to me at lunch, just asking how im doing, you know? like the normal way friends talk. and instead of being nice back or anything, i kinda mocked her a bit and was like 'yeah right, what are you even doing here' and walked away without saying another word. i still remember it hurt me so bad to do that. since then she never really talked to me again in school. and im scared if i try talking to her now its too late or shes gonna just think im trying to be fake nice or something. but also, im always thinking about the good times we used to have and it makes my chest hurt. im so sorry for being such a bad friend that day. i dont know why i had to be like that, it wasnt her fault at all. now i feel stuck because if i apologize shes probably not gonna want anything to do with me anymore. but the thought of just ignoring it and leaving things how they are also feels so wrong.