Loss of job after seperation agreement

I became separated at the end of 2009. At that time my ex and I put together a separation agreement based on the current lifestyle that we had lead while married. I agreed to pay well over the required amount of child support the state requires for our children, pay her support maintenance, and to pay for the residential property until it sold. My ex and children were to remain in the property until the sale was finalized. Also in dividing up the equity from the sale, I agreed to give her 70% and take 30% for myself.
Early in 2010 I became unemployed and am currently still looking for work. I receive unemployment each month totaling around $2k. Originally, as per our agreement I was paying $1211 for home and and $1300 child support and her support maintenance. Now I pay the home and $600 which leaves me a minimal amount left. She will not budge on this, she actually wants the original amount. I get the weight of our agreement, and will always care for children. What options do I have? She did not work during our 5 yr marriage, I did however put her through school for tow different programs to assist in employment. Also purchased a business that fit her skill set for her to run/operate, that we ended up selling so she could stay home with the kids.
Now she has had some fancy high cost attorney (no offense) write up a modified agreement with the new figures that I have been paying, which are in actuality still impossible for me to live with currently. And she wants to stay in the home, with me making the payments until she finishes school yet again which will sometime in late 2013. And then… sign all of the equity from the property over to her completely, the property which I have paid for for the last 5 years.
Does my lack of employment and economic hardship allow this type of scenerio to take place. Can I really be made to do this. I want badly to go to an attorney, but can’t afford it in the least. I left the marriage, I felt the guilt for a long time for my actions. Now the guilt is fading and the economic reality is setting in. WHat can I do??? I asked 50 times if she would let me come back and try for the rest of my life to make it better, she would not have it because of my current living situation. I understand that, but my only alternative was to live in my car until she made up her mind. I surely wasn’t going to stop payments to her for our kids and the house which they lived in. That means more to me than anything else. Please tell me what my options are. Give me the best case and the worst case. I have not signed the new modified agreement, I can’t.
Thank you for your time and understanding.

Unfortunately Separation Agreements are non-modifiable, and if you fail to pay she can sue you for breach of contract, though you do have the defense of impossibility. (This means that you do not earn or have the money to pay and the defense does not take into account your expenses or your situation at all).
I would suggest you try and negotiate with her attorney to reach a new agreement that you can live with.

Thank you so much for your reply. I guess my follow-up would be to request a clearer understanding of the defense of impossiblilty that you have suggested “(This means that you do not earn or have the money to pay and the defense does not take into account your expenses or your situation at all)”. Are you saying that the court will not take into account the cost of living that I require day to day? I have my kids for 10 to 12 nights a month and the days that are connected therein; what about my caring for them?
Also, what about the 50/50 division of property (which i agreed to give 70% of equity to other)? Does my unemployment deemed me unentitled?
Worst case, she takes me to court for breach of contract; what will the result be? Will the court take into account the fact that I have been paying her my income for the last 8 months, despite my impossiblity defense?
Again, thank you Erin. I do appreciate your time and expertise, this is a great forum.

Right, the defense does not take into account your expenses, just whether or not it is possible based on what you earn, to pay the amount in the agreement.
The property division cannot be modified.
I cannot predict the result in any court case, nor how much weight any one judge will give to individual facts.