If you truly fear for your son's life, then you need to call Child Protective Services. Don't wait to save money for a lawyer. Be proactive, and call Child Protective Services. If they find that your son truly is in danger, they will remove him from the home. And as long as you don't have anything against you, he should be placed with you. Another option would be Friend of The Court. You can contact them, let them know what your worries are, and they can schedule a hearing.
You do not require lots of money to get a child custody lawyer. If you have some little cash then I would advise you to borrow from friends or even family. You can also talk to the lawyer to help you through the case and pay him later. Alternatively, you can contact the child's support office in your area and explain to them about your financial situation to see how they will help you.
I live in Maine also. Look into pine tree legal services they have lawyers that work for free or low money based on what you can afford. also call dhhs (the department of health and human services.). If you feel your child is unsafe you need to have them look into it. You can call anonymously. I wish you luck. I have a little boy too.