Can’t make friends

So there’s this girl at my sixth form ( sorta middle school between high school and university in the UK) who I know and I cut her out of my life for being a horrible friend and incredibly immature person who just wanted to start drama.

Anyway so we’ve started this new sixth form and she is making it impossible for me to make friends. I thought it was paranoia at first but if I spoke to someone, she would and itd be like she was chasing me. Now if I’m in the middle of a conversation with a group she comes over, if me and a group of people go out after school she comes. I’m acting not bothered at all but she knows I don’t like her.

SShe’s started getting close to the same people i have, people I tried to become friends with since she made it impossible for me to be friends with another group!

Shes got people to add her into our group chat and it’s driving me insane. It’s like being stalked it’s impossible for me to make friends. I already struggle socially as it is. It’s actually ruining my experience at sixth form I don’t know what to do I feel so lost.