Is living in a house for no charge,instead of getting cash for child support a good idea? Or even legal? Or have I messed up my kid's life?

I do not make enough money to live in the city that my 2 children have been living in. So my X husband said he would let us live in a house that he has in this city, and he will continue to pay the mortgage, taxes,etc.. Because he is not able to sell it due to the economy and the loans owed on it. And if he tries to rent the house he wont be able to get enough rent money to cover the mortgage payments.Then the children and I will stay local, have a nice house that I can treat as my own.But he will no longer give me a monthly cash child support payment. Now that I have taken him up on this offer partially out of guilt because it is a bigger place with a pool and my children were so happy I did not want to disappoint them. But now I am basically broke and miserable because any time either the children or I do something he does not like he yells and screams at me telling me to get out of his house or he will evict me if I don’t hurry and get out of his house. Currently he is mad at me because I took my 16 year old daughter to get a tiny nose piercing. (I have one also) Otherwise she is a good daughter she has good grades,participates in school activities does not do drugs or anything illegal. She had a nice car that her father bought for her when she turned 15½. But when he told me he was evicting us he took the car back and turned off her cell phone. He screamed and yelled at her and me calling her a Whore, Slut and many other nasty things because of the piercing. We were both crying, she was apologizing to him for making him so mad and asked “Daddy, I will take it out” and he replied by saying “You are not my Daughter anymore” as he sped away in her car. But he did tell my son “Dont worry, I will come pick you up on the day I send the Sherriffs to kick your mom and sister out of my fucking house, so you don’t have to see it”. I never signed any papers for the house we just moved in our belongings and my x husband said that I needed to put the utilities in my name and pay for them. That was 4 years ago. Now I am scared, hurt for children,confused and do not know where to turn or what to do because I think I made a big mistake in ever moving in. Any advice would be appreciated.