I am sorry for your loss. I'm not a cat person, but I can empathize because I know how I'd feel if my dog were to pass away. There would be a big empty spot in my heart.
I've been through the lives and deaths of five dogs up to now. I'm on dog six, which is 14 yo; so she's no spring chicken anymore.
Anyway, each loss was saddening. And I had to go into mourning for a few months, even a year or two on occasions. But the fix for the sadness eventually comes with getting a new dog. Which is why I'm on dog number six.
Each dog was different than the others, but that was a good thing. Each one was unique and precious; and I loved each one. And, I think, each one loved me in return...at least they loved the snacks and dinners they got from me...of that I'm pretty certain.
So here's my advice, from a dog lover: give it a few months to properly mourn the loss of your calico. But then find a new cat that needs a forever home and take it into your home and your heart. That's how you make the sadness go away.
Don't look for it to be like your calico; it won't be. But look for the uniqueness of your new cat and care for it and it'll love you in return.