how do i stop cutting people off

After graduating from school this summer, I decided to cut ties with most of my school friends. I didn't particularly enjoy their company. They tried to reach out at first but eventually stopped. However, there's this one girl who keeps contacting me almost every day from different numbers. I did this with my middle school friends too. I had always been distant during our friendship, and at times I outright told them that I would cut all contact after leaving school but they never took me seriously. my past romantic relationships have ended in disaster too, because of my emotional unavailability. As I spend more time with people, I always get annoyed at every little thing they do. it's like I get an ick from them just breathing. How can I become more attentive to others?