Unfortunately, there is no such thing as a forgiveness letter. There is a form called an I-601, which is a request for what is called a waiver. It may sound just too simple to fill up the form, complete it, and submit it to immigration. DO NOT DO THAT. These waivers are very complex, and the form fools you into believing it is an "easy"thing to do. It is not the form, but what must accompany the form (laws, regulations, cases, and supporting documents which support your position and request for the waiver). So, it is not just the form with a filing fee, but additional documents which may take up to 20, 30, or sometimes I have seen them to reach up to 100 pages or more.
It is worth your time and effort to see and meet different attorneys and save your money to pay a lawyer of your choice to do this for you. Please do not try to do it by yourself, since you may hurt your chances, possibilities, and case even more.
Alejandro R. Lopez, Esq.
Law Office of Alejandro R. Lopez, P.A.
4465 Edgewater Dr.,
Orlando, Fla. 32804
Don't do any papers without an attorney ... this is quite complex.
FORMER IMMIGRATION LAW PROFESSOR -- LEGAL DISCLAIMER: This answer is offered for informational purposes only. It does not constitute an attorney-client relationship.
More information is needed.
If you were a lawful permanent resident, but were ordered deported for an "aggravated felony" for immigration purposes, then no waiver is possible. However, I agree with the first attorney that there is no such thing as a "forgiveness letter" for citizenship by naturalization purposes.
If you leave the U.S., then you may not be allowed back into the U.S. Unfortunately, you may even find yourself back in Cuba, where the country that you are returned to has diplomatic relations with Cuba.
If you have a final order of deportation, but the U.S. cannot find a way to send you back to Cuba, then you will likely not be able to travel outside the U.S.
If you are confused, then I strongly recommend an appointment or teleconference with a competent and experienced immigration attorney. The appointment may save you hundreds to thousands of dollars. In addition, you may not "self-deport yourself."
This is general information, not legal advice, and does not create an attorney client relationship.