Honestly sometimes guys genuinely don't think. I mean sometimes people just don't think. But in this instance I think he is probably telling the truth when he said he didn't consider how you would feel about it.

Although, is that better or worse?

Thing is you know what he did so the balls in your court, either you accept his version of events, let it go and move on. Possibly with couple counselling.
Or
You don't believe him separate for a while, get your head sorted then decide what to do.(Again possibly with mediation or counselling.)

Or you don't believe him, stay with him. bring it up every time you have a fight and use it as a sh*tty stick to beat him with, making you both miserable.
Or
Never speak of it again and continue as things are.

Hope you manage to find a way to sort through things. Best of luck.