I'm sorry to hear this, my cat passed a while fa and this is what I did: listen to lots of music thought of the great times we had with each other blew my nose a lot and cried really hard until I ran out of tears this may sound weird but I found listening to my preferito Musica helped me relax. Remember it may feel like te will never get over it but some giorno te will, I'm not saying te will forget about your special friend, neither have I, I am just saying that one giorno te will stop crying think of the happy memories and smile :) Eating a preferito Cibo may help too and watching a preferito movie o show.
My cat died to so fucking deal with it! ^ just kidding. My cat died a few months ago, what I did was put on my headphones crawled into letto and ate ramen la minestra, zuppa for about 3 days. That semt to help. Hope te feel better <3