Long term partner (5 years) with whom I have young children. The relationship isn't fantastic to be honest but he's never made me nervous before. He has form for being shit at communicating.
Backstory: I met him just over a year after I left a very abusive (In all senses) relationship which I still carry alot of trauma from. He knows all about it. That man left me in alot of debt, deliberately, and I'm still picking up the pieces now.
I was sat with toddler DD as she was watching nursery rhymes on YouTube, she was listening to a song called "don't open the door to strangers"
I joked to DP that I wish he wouldn't open the door to strangers without checking who it was first as one day it might be a debt collector. It was totally lighthearted.
He immediately got pissed off and started ranting about how he can open the door when he likes (the house is in my name by the way)
I was taken aback and said he was being ridiculous and asked why he was getting so angry.
Cue more ranting about how asking him to check who's at the door before opening it is treating him like a child and how bailiffs can't enter your property anyway 
I said It was a lighthearted joke and he's over reacting so I don't want to continue the conversation. He's still pissed off and storms out to go to work, swearing as he leaves the garden.
He just blew up out of nowhere.
Before anybody suggests it's because he's pissed off about my debt, he has had debt of his own in the past so it's definitely not that.
Can you help me understand what on earth that was about?