Searching for a JAFF book I read, HELP PLS

I have a JAFF book I previously read stuck in my head. Like a song that gets stuck, I need to reread the book to fix it! All I really remember is that Elizabeth is badly injured and has surgery on her head, including cutting her hair. When Lydia thinks this is funny, Mrs. Bennet cuts Lydia's hair. I think Mrs. Bennet cuts her own hair as well, to show Lizzy that hair isn't important, life and love are.
Does anyone recognize this one?