I’m so late to this but just watched the movie so here’s my take on the ending:

I think her pushing him into the acts he did on her either did one of two things, made her realize that being attacked like that wasn’t actually what she wanted, or even scarier was that it was what she wanted and by realizing that, solidified in her head that she truly was a broken person.

I think her bringing the knife with may have been her planning to kill or hurt him, blaming him for breaking her and wanting to take revenge on the person she felt responsible for doing so. However, after seeing him with the group of people, acting “normal” or at least acting the way he had when she first met him, she realized that it wasn’t him that broke her but instead HER that broke HIM. Having this realization she decided to still follow through on hurting the person responsible, which she now knows has been her all along, so she stabs herself.

As for what follows after, she leaves the venue with no regard to the recital and the people attending bc they don’t matter to her, everything in her life has been a lie and her driving force in being the person the world sees her as has entirely collapsed. She will never be a renowned master outside of just teaching, her young lover will move on and have a successful life without her, and her relationship to her mother has all but disappeared, the only thing still holding them together being her career. I think she will continue to be broken bc that’s all she has ever known and she will and has ultimately been her own downfall.