Why does my heart feel so bad?

I had a really bad nightmare that my dog was attacked and I could see her internal organs and rib cage just ripped apart and she was lying there staring at me clinging on to life, whimpering softly and I just cried and cried and I found out that she could be saved, but it was going to cost thousands of dollars that I just didn't have. It was so graphic and so real.

I woke up feeling so friggin traumatised.

My puppy is my life.