I'm thinking of ending a friendship of 8 years by deleting her number and quitting all group-chats she is in. I sometimes feel bad about it but I'm so relieved I have cut this person out of my life
Why would you do something that extreme to another person?
I became allergic to her, I can't stand her anymore
I'm sorry your friendship took for the worst, but you are going about it in the worst possible way ever. She doesn't deserve to be suddenly cut off after such a long relationship. She deserves a discussion with you to decide if you want to be friends still or not.
I will ignore you like she did.
I think that it might be more respectful to at least try to talk to her first. Maybe these are issues that can be resolved between the two of you.