I feel like this is the worst Christmas ever in my entire life.
The holidays can be very stressful. Can you tell me specifically why yours is this year?
I lost my dog before the season started and now I'm all alone in a season that is meant to be spent with family.
I'm very sorry to hear about your dog. That's a very sad event and explains why you are finding this Christmas to be a bad one. Maybe spending some time with your family or friends will help you feel better!
Screw it, I lost my dog and nothing can make me happy now.
It's okay to keep mourning for as long as you need. Just take care of yourself, and seek support if you need it from family. They would love to try to help you get back on your feet.