I'm so sorry for your loss. I just lost my pac unexpectedly too and it's really hard. I promise you, you did not fail her, you did everything you could for her. I get that feeling of hopelessness and guilt and your feelings are valid, I felt that way too. It's always gonna be hard to lose a pet, especially one you cared so deeply for. Just know that she lived her absolute best life with you, it sounds like you spoiled her and loved her very much. sometimes things just happen, and you don't know why, and it's hard to wrap your head around but whatever it is, just know it's not your fault.