Embarrassed myself at work

I agree with the previous poster.
Just tell him what you’ve told us.

If you have solutions for future events suggest them. ie if Julie gets trained to do x and Sophie gets trained to do Y then they can provide cover at these events.

Or that a ten minute pre scheduled break per hour would allow you to go deal with things, so the team would save them up for you for 50mins and nobody would panic. But that you may be a little late back.

Breakout rooms are also good for that as you (or your boss depending on who is fighting the fires) just don’t go on one while the rest do. Giving you time to do urgent stuff.

If he thinks you prioritised incorrectly then you can say you’ve learned from this experience. Although when was he expecting the day job work to be covered? After 5pm at night or something? Tomorrow? If he provides a clear steer then you’ll know for the future and he can carry the can when things go wrong and didn’t get fixed sane day.

If things are so urgent you need more staff. What would happen if you go off sick? You need cover for all posts. So perhaps additional staff required? Are you exhausted as doing too much for too long? Does he appreciate how much you do - or even know?

I’d turn this around. I’d go in today and speak to your manager. It doesn’t need to be and shouldn’t be combative, but I’d say something like:

“I was thinking about it last night, and long brainstorming sessions like yesterday don’t really work without cover do they! It certainly made me feel very stressed/concerned about quality control of tasks/ put me in a position where I couldn’t do my best work- and I don’t think that was fair. I think for next time it would be really beneficial for everyone if we worked out a cover system (or put in a midway formalized “break” to deal with anything urgent if you’re in a time sensitive response environment etc)”

and see what they say. Ultimately you were set up to fail, if they put you in a 5 hour meeting, didn’t arrange or have flex in the team for cover or contingency, and nothing could wait.

Why would your manager by annoyed by you doing your job? A 5 hour brainstorming session doesn’t sound like a priority to me tbh.

It's only work. Don't dread it but maybe there are things you could jendping to ensure it doesn't happen again - like making it obvious as someone else suggested that you ae available rather than trying to deal with your job when you should be in a meeting.

Do you have trouble asserting yourself? Are you a bit of a people pleaser? Or just a bit disorganised? Your manager can help you with managing expectations and work

As others have said, you need to commit to one thing at a time - either trouble shooting the team's work or the meeting. You cannot try and do both at the same time (as you have discovered!).

As others have said, just have a conversation with your manager to say you recognise that it was a bad day and how you would manage this if it happened again. Either asking for the meeting to be deferred, nominating someone else to deal with the issues that were going on outside of the meeting or asking for a half hour break from the (5 hr!!) meeting to go sort it all out, but only do that if you can then come back focussed on the meeting.

It sounds like a crappy stressy day, but just use it as a learning experience.

Presumably they were work issues that were cropping up.
Maybe your manager wasn't impressed at the rest of the team not being able to manage without you and disturbing you.

For long meetings like that, it's reasonable to ask someone to cover - and put their name on your OOO or Teams status - then go on 'do not disturb' or silence your phone.

When you say 'things cropping up' I take it this was nothing of life-or-death importance?

All you can do is admit you made an error of judgement and explain what you will do next time - go on 'do not disturb' and if necessary, ask someone else to be the point of contact for support during meetings.

You could, in mitigation, say something along the lines of wanting to be available to support your team and not liking to leave people unsupported - but you realise on this occasion you got your priorities wrong.

I’d speak to them first thing just say what you’ve said here

Why would you keep leaving a meeting with your manager? If I'm in a meeting then generally everything waits until the meeting is over.
If something comes up that is really urgent, the meeting is rescheduled for a different time.