You can draw off his account as an ex-spouse if (1) you were married at least 10 years, (2) are at least 62 years of age, (3) remain unmarried after the divorce, (4) he is entitled to receive social security (regular or disability) and (5) you are not entitled to a higher amount on your own earnings history.
If you are receiving SSDIB, then nothing should affect your monthly disability amount.
For additional assistance, you can contact your local State Family Independence Agency (FIA) or Department of Human/Health Services (DHS).
Also see if you qualify for free legal aide as Ms. Kadetskaya has indicated.
You would definitely need the assistance and advice of a family law attorney.
I would suggest going to local SS office first and find out your options. As far as reaching agreement, get a family law attorney who can help you with a settlement agreement.
The information you obtain from this website is not legal advice.