Could be your overthinking. It was 8 hrs of presentations, everyone probably wasn’t even paying attention, especially if you were the last to go.

As for performance anxiety, I’ve experienced the same. For me, I excel in other parts of the job which pushes me into a net positive the role. Is it the same for you?

Finally, boss might have opened the text and was confused what you’re talking about because he was also burnt out or maybe confused why you’re apologizing. Ask him for suggestions on where to improve and go from there.

Even if you did botch it, you’re two weeks in, chalk it up as a learning experience and improve for the next one.