I totally understand how you feel. I myself have lost several cats. Jasmine was 15 yrs old and died pretty quickly of kidney failure. Hodgie was 16 yrs old and died in my arms in the car on the way to the vet after being attacked and chomped on by a neighbors dog right in front of me. Bandit was 2 yrs old when he quickly died from UTI blockage. Same with his brother Simba, age 4, whom the vet said that it was not at all likely to happen twice from the same litter. Sheba, age 1, ran off and/or was stolen from my house in my absence. Roman, age 4, escaped when we were living in my car for 3 days (me & 6 cats) and I opened the door to get out. I looked for months and months for both missing cats, found Sheba at the place that found her but decided they were keeping her and not give her back, but Roman was forever gone. So believe me, I know how much it hurts to lose a furry child. But, somehow, that just doesn't stop me from continuing to adopt. Right now I have 6 cats (have had up to 9 at a time), Gabby, Milo, Blackie, Smokey, Muffin, & Sebastian. And, actually, I do still have Jasmine, Hodgie, Bandit, & Simba cause after they died, I had them cremated so they would still be with me til I die, then we will all be buried together.
I hope your little one is okay and comes back soon. Chances are pretty good, specially with the microchip, but if someone has trapped the cat (i've had a neighbor trap 3 of my cats before), it takes a few days to show up at the shelter. But most likely, it's out there struttin it's stuff (cats take FULL advantage of a freedom opportunity) and will re-appear soon. Good luck!