This is what happens when the Internet's obsession with overwhelming cuteness reaches its breaking point. You're lured into watching what you think is an adorable video of toddler who loves her little baby brother so much she can't stand the thought of him being less cute, and find yourself having a full-on existential meltdown.
A woman captured video of 5-year-old Sadie just after the little girl learns that her roly-poly baby brother is in fact going to get bigger just like her and her parents. Her cries of anguish that she doesn't want him to grow up, her hugging and kissing of his fat little head, her adoration of his cute little smiles, his sitting there ignorantly drooling at her, it's all too much.
And then as if that isn't enough, she cries out, "I don't want to die when I'm a hundred!," making the connection between his impending enbiggening and his--and her own--inevitable mortal end. OH MY GOD, NO.
Seriously, Internet, you don't have to go home but you can't stay here.