i dont know whether im being rude for dropping my best friend

ive been friends with this girl from yr7, until she left for a different sixth form. during yr10 and yr11, in our friend group, it kind of felt like she was the 'leader' but i still enjoyed spending time with her. there were times where she would say hurtful things and confronted me once because i was spending lunches with my music friends for our gcse. i have a medical condition and i told her about it bc she was my best friend, i didnt tell the rest of my friend group. one day i said that my back hurt to my other friends and they were like "is it because you have ....". I was really shocked bc i had never told them so i knew then my best friend had told them. i never said to not tell anyone but i kind of expected her not to spread it since its a sensitive topic. she started to change in year 11 when she got a bf and our conversations would be about boys and stuff even if i was the same person i was in year 7 if ygm. it was as if she was growing and i wasn't. i didn't mind this at all though. after gcses we went to a concert and there were a bunch of people vaping and smoking and she was like 'i wanna try it one day'. and obviously i was shocked, she would sort of dream about going to houseparties, drinking alcohol and for some reason she was really obsessed with sending her kids to private school and having half asian half white kids (she was asian). thats irrelevant but the point is, i could sense we were getting more and more different. when she left sixth form, i felt a bit freer, i dont know how to explain it. but when i look back now, i dont regret being her friend or anything, there were more good times than bad times. we didnt really text in year 12 but when we did it would just be about school and it definitely wasnt how it was before. she recently sent me a tiktok saying how she misses the old times. this is the problem, i dont know if im being a bad person to drop her because i just dont feel things are the same anymore and of course i dont expect things to be, we've grown since year 7 but im happy with the friends i have right now and me and her are just too different. its not just me who thinks this way, lots of my other friends have had similar experiences where theyve cut her off and said shes 'manipulative'. when i think about our friendship, i really enjoyed it but theres also been a lot of times where i would be exhausted. pls give honest advice.

I'd say she sounds like a bad influence. It's ok, everyone moves on. I'd also recommend you mention to your friend if you ever do this again that you don't want your secrets to be thrown into the open. If you explicitly mention this and they don't agree, I'd suggest having a reflection on your friend group. If you're in a different 6th form and she doesn't contact you reguarly, unless you do something about it, the bond will continue to drift apart. If you don't want to let go of her and you have the strongest comforts and sensation of being with her, go ahead and chat to her more. But this doesn't sound like the case, and I hope you strive to find friends, who are more aligned with your vibes. Good luck with your studies.

Seems completely reasonable to drop her. You're not obliged to be friends with everyone or to re-establish old friendships just because someone reaches out.