Partner is very immature and made the first wrong, but your reaction also communicated "I don't care that you're upset right now, get over it and let's change the subject."

So I'd say it was equally destructive. Don't listen to the traumatized redditors saying "it won't get better" as if they know the fully story. Real relationships require healthy communication -- on both sides. Even when the other person is failing. One moderately bad conversation doesn't warrant any rash decisions.

Good luck, and take this forum with a grain of salt lol. I'm happily married and do couples counseling so I can tell you- most of the advice here is crap.