Oh Mary, I’m so sorry about your cat. As a huge pet-lover myself, my heart goes out to you. It’s like losing a part of your family, and of course you’re going to be heartbroken. I know it’s particularly tough timing, since you’re just starting this new job, but I’m sure the people there will understand that you need a bit of time to grieve. Be extra gentle with yourself for a while, and remember that it’s OK to lean on your support network more right now. Certain times of day are going to be hardest, when the memories come back stronger (like when you get home from work), so maybe consider asking a friend or family member if they would be willing to talk on the phone with you when you walk back in your house at the end of the day so you feel less alone.
I’m glad to hear the new job is going well! And having two reasons to wear your amazing Halloween costume will give you something to look forward to.