A mistaken second chance

Today I sat for a mid-term test which is 40% of the total grade. It consisted of 3 essays. There was one question I entirely did not study for because I had strongly believed that it would not come out. Well, in a way I could have talked something about Freudian theory to gain me a little marks here and there but truthfully, I was just so afraid of answering essay questions that I decided to just skip the entire question altogether to save me the trouble of freaking out. Plus I had slept a mere 5 hours before and needed all the brain power I could get for the other 2 questions from which I could squeeze at least a few marks from. So I decided to give up that question.

Initially I thought the question was only worth 12 marks, which was why I decided to forgo it completely. I only found out later on that it was worth 35 marks. Then just now I received an email from my lecturer to a few of us saying that we did not do one of the questions at all and since she had previously told us the test was going to consist of only 2 questions, she was going to give us another chance and sit for a make-up question worth 30 marks which we have to complete in 30 minutes.

What should I do? Tell her that I had opted to give up the question because I did not know how to do it at all and thus probably give up the chance for a replacement question, or take it up on the pretext of having misread the instructions, as did the rest on the mailing list? Doing the former is devastating because now I know for sure I'm going to fail this mid-term while doing the latter will make me feel extremely guilty and is unfair for the rest. At the same time, if I decide to do it again, I'll need to prepare myself for another essay, which I really fear greatly.

Deciding to give up the question during the test itself was bad enough, why do I have to make another similar decision again?

What do I do? Help.