"You may possibly wonder why all this was not told you last night. But I was not then master enough of myself to know what could or ought to be revealed."

After reading the letter we come to these sentences at the end. It makes me wonder if Mr Darcy really was master of himself when he wrote the letter. He seems to give every detail of both "offences". Even down to the size of Georgianas fortune. It is no wonder it takes Elisabeth two hours to reconcile herself.