This is never how you want a friendship to end. At least I get the feeling that Tarumin will bounce back. She's clearly spent many a year bottling this up, and though it's a harsh way for those feelings to end, she has more mental fortitude than most! Good on her for having that burst of confidence to let it out, and to let those tears flow.
Somehow, I think seeing it through Shimamura's viewpoint made this more of a gutpunch than any alternative perspective for that reason: all you can do is observe it through the eyes of the one person who knows for certain that it is over for good. No glimmer of hope here.
Here's to you, Tarumi, and your admission to the Rejected by Childhood Friend Club. You'll be in good company.