How to fight fair?

I'm writing this post not because I know the answer, but because it's something I'm working through.  N and I got into a disagreement.  Actually, he got mad at me for what I think was a stupid reason.  He figured out (a month after the fact) that I threw out an expired carton of eggs.  Note:  he was just going to use them today which would have been a month after they had already expired.
Nonetheless, the argument ended up being about me invading his space, changing things in his life, etc.
He had what I would consider (for lack of a better expression) a $hit fit.
If someone comes at me, I most often take a step back and don't engage.  If I'm pushed to far, I'll snap.  I didn't get to that place this time around.  However, when N came back from storming out to get a new carton of eggs to make breakfast with, he was ready to say he was sorry and move on.  I wasn't.  I don't rebound that quickly.  I never have.
This transition is a challenge, but I know its an inevitable part of the growing together process.  Patience, KG.  Patience.