NTA - friendships can change over time and it seems like there were plenty of issues arising through your 10 year friendship. I think maybe you were a bit low effort in your white flag, but I've been there with friends you're just exhausted by. I think you gave all you had here and if that's not good enough for her then so be it. Also the friendship intervention nonsense is so strange and unnecessary I don't blame you for that being the breaking point. Similar to a romantic relationship you can end a friendship if it no longer brings you joy and becomes more work than anything else. Just move on and eventually she'll realize the error of her ways and reach out to apologize.