My (28m) wife (26f) has the world's smallest spending problem and it's driving me nuts!

Every time she leaves the house she comes back with some kind of tchotchke or bric-a-brac and says, "it was only three dollars!"

We have a small two-bedroom apartment and we're very unorganized. The second bedroom is effectively a storage room where we have just tossed all the things we don't use but can't throw away. Every surface of my home is cluttered with some sort of Tupperware or pizza box or random knickknack.

I've never broached the topic with her, because she's very sensitive, and I just don't want to deal with it. Today, when she left the house to pick up a prescription, I casually told her not to buy anything. She said she might get an energy drink but nothing else. Then she came home with a glass mushroom and a plastic light up cloud. Why?? I specifically said not to do this and she said she wouldn't.

I didn't blow up or get mad, I just didn't say anything when she showed me her purchases. I think she could tell I was disappointed because she started getting visibly anxious. A few minutes later, I brought up my frustration with her spending habit. She burst into tears and started rushing around the house saying she would return them. I told her I'm not upset with her, I just want her to stop cluttering the house with things we have no room for. She ended up running off to the bedroom to lie down, slamming the door on the way.

Ultimately, I think I'm insecure about not being able to afford a bigger place that could sustain her incessant purchases. But the fact is that we don't really have the money for her to spend this frivolously, even if it is only three dollars.

I should add, I love my wife very much. She's an excellent partner in so many other ways. It's just this one thing that's bugging me.

tl;dr: my wife keeps buying tchochkes that we don't have space for, and she got upset when I brought it up

Edit: I want to clarify a bit now that I'm in a less emotional headspace. I feel I have mischaracterized my wife's communication skills with this single anecdote.

Yes, my wife is a bit sensitive, but usually this manifests more as anxious hand-wringing than open tears. She has been a bit more emotional than usual lately, partly because her work has been very stressful—she's a mobile mental health crisis worker—and partly because we haven't been able to get her medicine due to a national shortage.

Even with those things working against her, she's generally a fairly level-headed person, and this afternoon's episode was atypical. We usually communicate fairly well and are both able to take criticism on stride.

After we had both calmed down, we had a rational conversation. She has agreed to pare down the various trinkets she's collected, and we'll both be focusing on cleaning up around the house.

Having now read several comments, I appreciate the helpful advice that has been provided regarding how to maintain a more orderly household. And many of the things people have said that we were already doing.