How old is your kitty? We have 2 that are almost a year old, and I am stressful about leaving them also. I decided that boarding them at the vet was NOT an option, but they really need to be check on while we are gone. This is our first trip away for more than 2 days.
We have local boarding companies that will take your cat into their homes, but these are expensive for me. That could be an option for you. Some of the people who work at the vets office may also be willing to do this, so they are well trained, and will give your kitty lots of love - I just didn't check into that because I have a couple of friends who plan to stop by.
Because I have 2 cats, I am also concerned about how quickly the litter box will fill up. I've bought some liners to put in the box that have lots of slots in the bottom. You put several liners in the box, then the litter. As you need to clean the litter, you just lift out the top liner. All the "stuff" stays in the liner, while the unused litter falls through the slots back into the box. My friends can just do that and throw away the used portion - no scooping, etc.
They will stay and play with the kitties for a little while, make sure they haven't dumped out their water/food, aren't sick, etc. They should be fine. I assume they will just be mad at us when we get back - and we will have to make up for it with LOTS of snuggles.
Hope this helps. If you are really worried, look into boarding-type place that takes cats into their homes - not a kennel. Or, ask your vet's office for recommendations.
Mary