Child Support and the Bio-mother

I am completely frustrated. My husband's wonderful ex wants more money. Fine he recieved a raise but the reason I am mad is because they are going to use our income tax and take the money that I made into consideration. I have three kids of my own to raise. What gives her/them the right to do this? I can barely make ends meet now with gas and oil prices. I have a large home but now I am going to be at risk of losing it. I would be fine with selling it but the market is really crappy. I can't lose my job because it pays better than any in my home town even with the traveling but I have to drive 45 minutes to get there. My kids all ready go without because I believe in fairness but you know I am getting tired of it. I am having a hard time keeping the faith. My 17 year old wrecked our truck so we had to get a new/used vehicle(she was okay). My 8 year old may have thyroid issues and all three of my children need glasses. The 17 and 8 year old need braces and I am going to have to be on something here pretty soon to keep sane. I just don't know what to do. I have tried to reason with this women and have been nothing but nice because I believe in the whole karma thing but it is getting really hard. I didn't grow up like this. I was raised with empathy. I think she was raised by the devil. Well must get back to work. Needed to get this out because I am having a hard time concentrating.

Completely Frustrated!!!!