Was it an example of gaslighting? Could very well have been. You say this sort of thing has happened before. If there's a pattern then, yes, it could have been a passive-aggressive show of annoyance on her part.
Maybe you could have asked if she wanted to take a look at what you were going to throw out, that's true. But her response is on her and it (if that's what happened) is not a mature or healthy response.
I'm just gutted. I feel a defeated and thinking maybe i could have done things better.
I get it. I've been there. So many times when my H was upset about something, I would beat myself up for having messed up somehow. But, over the last year, I've learned some things:
1) People make mistakes. Usually, they're not big ones -- especially not nearly as big as my H would make them out to be. Now, when I make a mistake, I acknowledge it, give a sincere, simple apology with some validation and move on.
2) Apologizing over and over, groveling, ruminating, constantly worrying about everything I do and say -- it just makes me look and feel weak. And, the weaker I feel/appear, the worse relations with my H get. When I'm strong, he feels more secure and doesn't lash out nearly as often. Even more importantly, I feel secure and confident and ready to handle whatever happens.
3) I'm responsible for my actions and responses. He's responsible for his. If he chooses to act in a way that's harmful or immature, that's on him and I let it go and roll right off me -- and if there are consequences, those are his.
Anyway, back to this particular situation. How are things now? Has she seemed really upset about the box issue? Have there been other problems lately?