Riddled with anticipatory grief

So my mom's one dog is being put down tomorrow. I'm feeling a lot of anticipatory grief about it, even though she wasn't my dog. She's been a part of our lives for the last 12 years. Over and above this, it just reminds me that my pets are next.

So my mom's dog was diagnosed with a mast cell carcinoma in September last year. She's at the end of her battle. My dog was diagnosed with Lymphoma in November and although she's doing well, my time with her is also limited.

My mom and I have been going to the vet together, for our dog's respective treatments, and now the next time I go, I go alone.

I'm just sad for everyone. Sad for our dogs. Sad for my family. Sad for me. These animals steal your heart in a huge way and they always end up breaking your heart.