I agree with the suggestions put forth by both SS Moderator and ablacksheep, I couldn’t have phrased it better. It’s always important to be honest with your partner, especially about something that is affecting you this badly, and of course that’s only natural since we all need a break every now and then. Your need for some down time is very reasonable, and since you’re worried of hurting her feelings by telling her that, I think your wife would be understanding. As long as you communicate your honest thoughts while still showing her that you understand her position and feelings in the matter, it’ll hopefully make the transition smoother and you’ll both find a solution that suits you together. Instead of telling her to “back away”, ask her to “help” you.
I undersand how worried you are of hurting her or causing trouble, but you should keep in mind nothing will become better if you keep your thoughts to yourself. It’ll be like filling air into a balloon not big enough to handle it, over time it’ll fill to the point of having no space and end up exploding. Don’t push yourself to reach that point otherwise the discussion will be much, much harder to have, let alone you’ll be past the point of exhaustion.
Practice telling yourself what you want to say to her, it could make it easier for you to phrase your words better and to counter any parts that you think could sound harmful. If you think telling your wife you need some “alone time” is what could upset her, you could start by having some time to relax together at first, maybe sit and watch a movie together or take a walk outside or simply eat dinner together. I mean spending some quality time together, but not neccesarily working and doing tasks or chores. Then if you still need more alone time, you could honestly tell her that. Emphasize how important it is for every person to relax and have a little break, and the positive impacts it has both mentally and physcially.
When you want or need a big change in your life, it always helps to take things slow, one step at a time, especially if you want to avoid being overwhelmed.
I hope this helps you, and I wish you all the best!