My dog passed away and I can’t stop blaming myself.

This is incredibly difficult to write.
I’m 20 years old, and when I was 8, me and my family adopted a dog.
For all those years she was everything to me. A best friend.
She was a senior now, and I knew her day was near, I just didn’t want to see it. It was hard. We had to give her subcutaneous fluids every other day, and lots of medicine. But we did everything we could.

I had a trip scheduled to visit my family in another state. It would be my first plane trip alone ever. I was excited.
My trip was scheduled for last Sunday, and on Saturday, my dog felt sick. Suddenly, she was stumbling and struggling to walk. I was so scared and worried. But, after about an hour, she started to walk normally again. I thought it was just a scare even though I was extremely worried. I couldn’t stop thinking about: I can’t go on that trip.
But my mom said that I should go, it would be good for me. That she would be taken care of. I said goodbye to her before leaving for the airport and I asked her not to leave. I memorized her face if god forbid I didn’t see her again.

I went on the trip. For days I got updates, from my mom and my neighbor.
She passed away on Thursday. I wasn’t there.
My mother works during the day, so we asked for our neighbor and friend to come to our house when she could during the day to keep an eye, feed her, and update us. It was my neighbor who found her.
My mom said she wasn’t telling me everything in the updates to keep my peace.

I hate myself. She passed away all alone because I was in another state.
What if she gave up because she felt abandoned by me? What if me not being there led her to loose strength?

My mother keeps saying I can’t blame myself. That she was already sick. That me being there would only cause me pain.
But I can’t stop.
My mind keeps saying: she passed all alone because you weren’t there.

I’m so ashamed for going on that trip. What if, wherever my dog is, she’s upset at me?