How long can I keep buying supplies and grading until midnight?

You call this managing. It is not managing — it is paying, out of your own pocket and your own hours, for a job that should not cost you this much. Call it what it actually is. No one forced you to buy the paper and the pencils, or to grade past midnight. You chose it, because the alternative felt worse at the time. But every choice has a limit, and you have not set yours yet. That is the real gap here — not your competence, not your care for the students. Here is what is within your power: what you spend, what hour you stop working, what you agree to tomorrow morning. Start there. The school will not fix this for you. If the weight of it has started to feel like more than tiredness, say that out loud to someone outside your own head — a colleague, a union rep, a doctor. That is not weakness. That is sense.