What do you even say back to Yohan on the first message?

I think I went in without a plan and just froze a little. The setup has you already having corrected him in class before the chat even starts, so he's furious from the first line and it feels like there's no neutral opening left. Maybe I'm overthinking this, but do you apologize, double down, or just try to change the subject? I don't want to break the scene by being too passive, but I also don't want to escalate it into something that goes nowhere.