I came here as a small child without a choice and have been denied an opportunity to be a Citizen merely because the laws said so.
Katy,
There has been a lot of good advice given here and also some rather unsettling stuff too.
Here's an old person's take on this. Try to stay calm and think positive as I believe deporting is almost totally out of the list of possible outcomes.
There is no point in self-recriminations for what has been done, whether it was smart, wise, good or bad so get those thoughts out of your head. They are in the past and cannot be undone.
The wheels are in motion as you have already written the statement and handed it to the IO.
Let USCIS handle this first stage and see what transpires then deal with the next step. Who knows it may not be a problem.
I would not be getting and Infopass or writing more letters at this stage as the outcome may be favorable.
I would be looking for a good experienced immigration Lawyer but not hiring them at this stage. Do some solid research and make sure they are well experienced. I would go with a small company of maybe one or two Lawyers in the firm. Large Law firms will push small cases to junior Lawyers who may not have the experience yet. Just my experience and opinion mind you.
When USCIS contacts you with the results, then go to the Oath ceremony or hire that Lawyer and keep your fingers crossed. As has been stated since there was no gain to claiming to be a Citizen I believe your case will hold. If it is not approved by USCIS then almost certainly it will be upheld on appeal.
Stay calm and deal with each step as it happens. These are things you cannot control and getting upset over something that may NOT happen is not a good plan. Good luck and my thoughts are with you.