Are you living together? Who is the child with now? If you're not living together and you have the child then you just need to take control of your life and leave him out of it?Don't call him, don't go see him, do not invite the drama into your life. Do not ask him or his mom for help of any kind, and let your life be YOUR business. You may be trapping yourself by being too dependant on them.
Are you married or were you? If so, you will have to deal with the legal aspects of custody. If not, he will have to prove that he is the father even if he's named on the birth certificate. Most states favor the mother in these cases, given that you are a fit parent, not abusive to the child, can support him, and are not on drugs or involved in anything illegal. Running away will only get you into trouble. Kidnapping is a federal offense and it gets worse if you cross state lines.
Is the father abusive to you or your son? Verbally or mentally? Physically? Abuse of any kind is tough. We condition ourselves to believe what we are being told about ourselves. We tell ourselves that we deserved the names we're called or that we asked for the bruise on the arm. Though it's terrifying you have to get out. Call the police, let them take him in and get out during the 24 hours that he's gone.
Honestly, if you're waiting for the right moment to leave, you're never going to find it, you just need to step up and do it.

you dont have to run to another state if you dont want to. you just have to find another place to live and stay away from him. you can file for full or partial custody yourself. dont let them scare you in thinking theyre going to take your child away. what would be the basic of that.
why would they not want you to go to school or work?

I can guess why they don't want her to go to school or work. They either have the view that women should be subservient and obey men at all costs, and don't want her to realize that she is a person with value that can learn something or he may want to keep her where he can watch and control her. As long as she can't get 'out' to be with other people, then she is less likely to be empowered with the knowledge that she can possibly survive without them.

What kind of relationship you have with your son’s father? Are divorced? If not, let the court decide about the custody of the child. A child needs the care of both, don’t try to go away from your child, try to get the custody.