NTA but I think your boyfriend just poorly articulated how he perceived your statement. A chit chat is a casual conversation, so you said you cleaned up a mess while he casually conversed with his mom.

His reaction came from feeling attacked. He thought you were complaining about cleaning up while he casually conversed. He perceives chit chat as a casual term (small deal), and he perceives cleaning a mess as a big deal. And the juxtaposition of those ideas to him felt sarcastic or aggressive.

Clearly that wasn’t your intention. Clearly (to everybody in these comments) you’re not the asshole here.

What I’d do if I were you is think about if he has a reason to believe you were being sarcastic or aggressive, like if you get those attitudes often. And also consider if he has a history of becoming aggressive over trivial things. He may have an anger problem, or an insecurity problem. He may come from a household where cleaning up someone else’s mess came with a guilt trip, and he might be lashing out at you for thinking you were guilt tripping him. That’s something he’d have to work on.