Non-modifiable usually means just that. As you chose to ignore the instruction to identify your state, nobody here can look up the laws of your state. I suggest you consult a local lawyer about your options.
Sorry Mr Knowitall, my state is Illinois. My point is - I had to pay maintenance because at the time of our divorce, she was not well enough to hold a job to support herself. Now it appears that she can work, but is electing not to.