Well whose fault is this really? How can you be to blame for doing the work of 2 people and working double shifts for 7 days in a row?!?!

So you made a mistake and think they want to point the finger at you? What part of management would not sit back and think hang on, we've pushed our employee too far with the work load.

I'm not sure about the employment laws where you are and I'm sort of thinking that maybe you're casual as opposed to permanent? Not sure if you have a contract with them, if any.

I'd advise, for the time being, say as little as possible unless spoken to about this situation because you are emotionally vulnerable and you don't want to start saying things that might be adding fuel to the fire.

I'm sorry I don't know what external support you may have over there. Anything like an employment ombudsman if it comes that? A union? (I'm suspecting not...) Surely there must be a 3rd party who can support and advocate for you, if need be, for being overworked and doing the job of 2 people leading to your mistake?

I'm sorry you're in this situation.