IAmJointCommission's journey

I recently accepted an offer for a corporate job that seems perfect for my career and is conveniently located for my commute. However, I'm currently facing a challenge with their thorough background check process. I expected the usual drug screen and criminal check, but they are digging much deeper than I anticipated. For the first time in my job search, a potential employer is looking into my past employment history. I listed a job I've held for ten years, but it was always under the table, which I now realize was a mistake. They have already reached out for more information and I have a background check specialist emailing me for documents related to this cash-only job. They are requesting a W2, pay stubs, IRS forms, and other official documents that I simply do not possess. I'm at a crossroads about whether to come clean and explain that the job was under the table. I do have other restaurant jobs where I can provide W2s, but I included this one because it met the five-year requirement, and I was being a bit lazy in my application. This situation is quite stressful, as this job opportunity could significantly improve my girlfriend's and my lives. I'm seeking advice on how to navigate this snag and whether honesty about the under-the-table job is the best route to take.