Sorry you're struggling tonight. 15 years, that's a decent life for a kitty. I once had a bunny that was with me 16 years he still visits me in dreams sometimes. Can you find something to do to get out of your head for a bit? Are you able to concentrate enough to read a book or talk to a friend?
Holidays are tough for many of us. Hang in there, it's almost over.
The holidays are terrible for folks like us. Many of us struggle with the holidays. "Should I contact PoA? Should I send a Christmas card? Should I send a gift? Last Christmas/NYE were so wonderful..." Four months of NC - give yourself a standing ovation. I mean that.
I am sad to read about your kitty passing over the rainbow bridge It's hard losing our friends that way. You are not alone in feeling that loss - like the folks above wrote. I too had a special friend pass over the rainbow bridge a few weeks ago so I share your sadness.
You are doing okay - please post more if you are able. We're here for you.