I miss my dog

My dog is 5 months and my family was very fond of him, we used to be distant and quiet but our dog brought radiance in our home. We would play with him, talk about him, take pictures of him and laugh at his cute reactions. But yesterday an accident happened, my dog fell down the stairs back first and our initiate reaction was to take him to the hospital, so they did and the vet told us that he wasn't breathing properly so they (I was fast asleep when this happened because of assigned work) had to leave him there. On the afternoon my siblings went back and gave him his favorite toy and he wasn't reacting much but the vet told us his condition stabled so we can be at ease but however the x-ray they did was blurry so they were unable to say what was wrong, then my siblings went home again because there were a lot of people (it was only me and my siblings at our house because our parents were at my grandparents to take care of them). I felt guilty so I wanted to come with them to the vet the next morning but I had classes so I stayed at home. And at 10 am while they were traveling there my oldest brother got a text that our dog passed away. All I could do was cry and cry because I miss him. My other two of my siblings arrived late because it was far and because of traffic and they texted me that our dog is gone. Everyone here was blaming their selves like how he should've guided the dog down the stairs carefully, or when they could've at least seen him if they went there early or if I tried to go there when he was taken I could've at least told him that I love him so much more than anything else. He was the best dog I could ever be with, I don't know how I can cope up with everything right now, I feel like he's here but he's not. I miss him so much.