If unauthorized employment is excusable for US citizens’ spouses, how can I be hired since I have to fill out an I-9?

While it may be true that unauthorized employment generally will not stand in the way of a successful marriage-based adjustment of status application for a foreign national married to a U.S. citizen, that does not provide protection to an employer for hiring someone who is not authorized to be employed. I recognize that the costs associated with the adjustment of status application process are substantial. Nonetheless, that is the way that a foreign national who has overstayed permitted temporary stay in the U.S. through the VWP, and who is married to a U.S. citizen, may become authorized to be employed. It may be wise to consider borrowing money for the application process so that you may initiate the case - within approximately 90 days of filing the suite of applications you may expect to receive an Employment Authorization Document (an "EAD" or "work permit") that will authorize you to be employed while your adjustment of status application remains pending. Of course, there are many other details that may have an impact upon adjustment of status eligibility. There really is no substitute for you and your spouse to consult with an immigration attorney who, after learning all of the relevant information, could advise about eligibilities, options and strategies to attain your goals, and who then could offer legal representation in the often complex application process.