Will I be deported in this situation?

You have a sticky situation in which I do not see an easy answer if you take affirmative action. Your choices appear to be filing an I-751 at this time with the explanation that the untimely filing should be accepted because USCIS made the error – but you would have to prove entitlement to the application on the merits. If you apply for citizenship, an immigration officer is likely to catch the error at interview, and probably request that you file an I-751 at that stage or possibly refer your matter for removal proceedings. (I believe that a reasonable officer would give you a chance in light of the USCIS error). Due to the limitations of the Lawyers.com Forums, Alan Lee & Arthur Lee, Esqs.’ (the "Firm") participation in responding to questions posted herein does not constitute legal advice, nor legal representation of the person or entity posting a question. No Attorney/Client relationship is or shall be construed to be created hereby. The information provided herein by the Firm is general, and requires that the poster obtain specific legal advice from an attorney. The poster shall not rely upon the information provided herein as legal advice nor as the basis for making any decisions of legal consequence.