I feel so guilty that my bird died?! Help?

I open my parakeets cage to let my bird fly in my room like usual. Ive had her for 4 years and wanted to let her spread her wings for a hour. I put her back and forgot to lock the door to her cage and later that day when I wasn't home, my cat came into my room and opened it and scared her downstairs. She flew into the nook where my dogs were and my dogs ate her. I feel terrible and Ive been crying, I'm so sad. That she had to go threw the horrible pain and fear. I can't forgive myself please help:( what should I do? Do I need real help? I would of never done this on purpose, I feel so guilty and sad I can't stop crying! :(

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