Single mother

I dont know what to do. I just had an argument with the father of my 8 old month son and he ended leaving me and my son alone. We were doing fine. But his ex control his life like us to pay our own bills apart. We used to pay bills together and help each other but when his ex ended talking nice with him and then she seek him for money or steal his check. When he come to me and then he said that he doesn't have money that he pay his payments but he lied. Because I know his payments and one day when he got paid then we go together to pay the bills and he tell me how much he has. But things changed later when he goes to his ex house everyday to see the kids (they are teenagers kids already in high school over 16-23). I don't know what to do if to seek child support. But his name is not in my baby birth certificate. I live in Texas.