I get so tired of having to be the giving parent

When you are stuck co-parenting with a selfish opposite there is really no time for me to ever worry about my own feelings because my son's dad puts so much pressure on him to be with him and continues to tell him that he doesn't know what he would do without him. My son carries so much guilt around with him because of his dad is constantly pressuring him about everything. If he really cared about his son he should ask himself why he would want my son around his (anti-ever get my life together girlfriend) So if he loves his son you would have thought he would have said a couple of years ago like....look son I need to get some things together and I want you to stay with your mom for awhile. BUT NO he has subjected my son to everything that has went on in that house and I am so pissed and him for that. I never wanted my kids to have to grow up before their time and learn about things that they should never have to worry about at his age. I know it has to be hard on my son to go back and forth from one week to the next. I think I am going to encourage my son to choose one place or the other to live because he will be 12 years old soon and I much as I want him to pick to live at my house I am not going to tell him that and I am embracing myself for the worst because that is all his dad ever tells him. His dad also makes him feel inferior to all of the other kids that he has living in that house that are not even his kids. So regardless of my feelings or what I think is best for my son I cannot watch him go back and forth and be so unhappy. I have tried to take this case back to court but as my ex always puts it he will make sure I don't have a pot to piss in after that. I cannot afford to pay for an attorney and I don't qualify for legal aid which I still don't understand that, when I don't have a job.