I knew there was a case about it so I asked around. Here is the url.

http://www.supreme.state.az.us/opin/pdf2007/cv070019pr.pdf

Basically, in 2007, the supreme court in Arizona (your state?) says that for arizona, where people say in thier decree that it's non-modifiable, then it's non-modifiable. In this case, Waldren entered into an agreement for 5 years worth of alimony at $1000 per month. A year later he became totally disabled and unable to work, was getting $1300 per month in disability payments. He asked for relief from judgment on the basis that at this point the requirement of making him pay a thousand per month for the next 5 years was horrible. The court said basically that he made this agreement, signed that it was non-modifiable, and so he's stuck with it.

I'll be curious to know if you can change that.