Welcome to the forum family, @
juliacavies. I do wish it was under better circumstances.
You'll find no other place that better understands your sense of loss, other than this forum. That's one of the reasons we're all here, because of our devotion to our little furry family members. Most of us have lost one, others more than one. I myself had cavies as a child and don't remember much of them, other than their looks and their names.
My first as an adult, I lost a year and a half ago. He was so very, very special to me that I'm still not over his loss. I know I never will be. That said, time has made that pain a little easier to bear. Time may or may not heal all wounds, but it does make them somewhat easier to bear. Grieving the loss of a beloved pet, even "just a rodent" is natural and whether or not anyone in your circle understands it is irrelevant. What you feel is what should be important to you.
I would like to offer my most sincerest condolences for the loss of Chewie. It hurts. I know. We all know. I'm sure he's at the Rainbow Bridge now, making new friends, playing in the sun, and eating whatever he wants. He will wait there until the day you come to get him. In the meantime, cherish the memories you have of him. In that way, he will never be gone.