Hello. My name is Marc. I'm a licensed attorney and I will be happy to answer your question.
I can imagine how frustrated and anxious you must feel! Fortunately, there is a very plausible solution in your circumstances. It's called an Offer in Compromise, which could reduce your tax bill by as much as 75% and permit you to pay off the remaining amount in affordable installments. Let me explain further.
First, you can find the instructions and application for an offer in compromise here: https://www.irs.gov/pub/irs-pdf/f656b.pdf
An offer in compromise (offer) is an agreement between you (the taxpayer) and the IRS that settles a tax debt for less than the full amount owed. The offer program provides eligible taxpayers with a path toward paying off their tax debt and getting a “fresh start.” The ultimate goal is a compromise that suits the best interest of both the taxpayer and the IRS. To be considered, generally you must make an appropriate offer based on what the IRS considers your true ability to pay.
Before your offer can be considered, you must (1) file all tax returns you are legally required to file, (2) have received a bill for at least one tax debt included on your offer, (3) make all required estimated tax payments for the current year, and (4) make all required federal tax deposits for the current quarter if you are a business owner with employees. Your offer may be returned if you have not filed all tax returns you are legally required to file, or are not making all required estimated tax payments and/or federal tax deposits.
In order to be eligible and to receive the largest reduction in your bill, you should provide all evidence of your inability to pay. For example, late notices for utility bills can be quite persuasive. After all, if someone cannot afford to pay a water bill on time, it's unlikely that person can pay other non-essential bills on time. Discuss the ways in which your disability hampers your ability to pay. Mention any and all reasons why your outstanding tax bill cannot be paid.
Once it is determined that you are eligible, you will be contacted by an IRS rep from their offer in compromise department. Believe it or not, I have heard from a number of sources that these reps are actual human beings who take the time to understand people's issues. They may request additional documentation to support your offer. Ultimately, once they have all the paperwork, they will either agree to your offer or they will make a counter-offer for a higher amount. Either way, if you truly cannot pay your tax bill, the amount you owe could be drastically reduced. Furthermore, the outstanding amount will stop accruing interest and penalties (which are ludicrously onerous!). Also - even while your offer is pending, the phone calls will stop.
I wish you luck in this endeavor! Please let me know if you have further questions. If this helps you to better understand your issues and options, please be sure to rate my answer, since that is the only way I can receive credit.