Being taken advantage of ?

I have been in a relationship for 5 yrs. I have 2 kids and my fiance has 1 child . My kids are 19 and 16 his little girl is 6. I had a surgery on Aug 2011 that has left me disabled before that I was working full time and paying most of the bills including food and the stuff for the house. I worked for 3 1/2 yrs. Then I lost my job due to my disablility I fought for disability for almost 2 years. I get shild support and food stamps at this time that I was not working and helping as much as I could. I am now on disability and still get child support I buy all the food and the fuel for the furance, the cell bill, the cable and internet bill. By the time the middle of the month comes by I run out of money. i also have a cleaning lady come in 2 a month to help with the cleaning because my fiance does not help out and if he does it is few and far between. We sat down and did a budget and we are spending money that we don't have. When I say that we should split the bills including food right down the middle he get upset and throws in my face that when I was not working he took care of everything. While I was not working I was taking care of his daughter and my kids cooking cleaning washing clothes making sure that everything in the house and the mowing and the snow removal was taken care of. With my PTSD he thinks that it is fun when I get afraid because of noises of things that he does. I am in therapy but I really feel that I am being used and I am teaching my son bad habits. I am thinking about leaving. He is also verry rude to my son and they act like brothers more than an adult child relationship. He does want to split things down the middle because he says that he should not have to because when I was not working he took care of everything. I also deeded my car for him so that he had a good vechile to go back and forth to work. He had ran down his dads truck into the ground before his dad took it back.