Most self-blame is conducted using information the accused never had. You are trying a version of yourself who did not know how any of it turned out, on evidence that only arrived later.
Given what was on the table that week — the tiredness, the pressure, the things you had been told by people you trusted — that person made a choice that made some sense at the time. It may still have been the wrong one. Wrong and understandable are allowed to sit together.
Forgiving yourself is not a pardon handed to a criminal. It is closer to correcting the record about who was in the room and what they could actually see.