What can I do, I can no longer pay my ex maintenance fee?

I have paid her maintenance fee faithfully for 8 yrs now since our divorce but due to my health I can no longer work. I have severe pain in my hips and back and have difficulty walking. I have also been diagnosed with early dementia. I wrote her two years ago explaining this and she wrote back saying she understood and would not take it back to court. Now after two years she claims she did not understand this to be a permanent thing and wants me to start paying her. She claims she talked with an attorney who then filled out a violation petition but she asked her to hold off until she heard from me. my ex worked for the 8 yrs I paid her and then for the two yrs I did not pay her. She is also threatening that they can also get the money from the two years I didn't pay even though she told me it was ok that I didn't. After bills I have approx. $350.00 to live on for three of us. that has to pay for food, gas, home upkeep, prop. taxes, clothing etc...I am worried that they might put a freeze on my accounts. I get SS and my retired military pay of 20 yrs service of which I was not married to her at any of that time in Service. If she gets at my money we will have nothing to live on ourselves. She is old and wants to stop working. I have dr's order that I can't work. I live in Oregon, she lives in NY. I don't know what to do and this is very difficult on me since my memory and concentration is affected by the dementia. I was awarded the divorce on cruel and inhumane treatment by her and she has bled me dry from the beginning till now and still wants more. She got everything and I walked away with nothing but her bills, paid her att. fees, her taxes that she made sure of. paid for her move, her furniture etc...When will this all stop? The divorce decree does not have a time frame nor is it labeled anything but maintenance fee written on it. We were not told how long I had to pay. I believe she wants more money now since her Son just got out of prison after 10 yrs. and I think she wants to help him out with my money. She gets SS, medicare, she is eligible for Medicade and is eligible for SSI, food stamps and I believe she is still working but not sure. Any advice from anyone who has dealt with this. Not to be rude but please do not respond if you are a woman on her side. I need help not your assumption that I am a dead beat. I am not and have not been. I am in a desperate way and can barely care for my own families needs now and we go with out so much and have for 10 yrs. My ex was also awarded my Survivor benefit plan so if I die, she gets the money and my new wife gets the bills. Where is the justice? I paid for the SBP for years, she was not married to me while I served the 20 yrs in the Air force but she gets the money? I am desperate for some advice. Thank you.