A question about retainers for child custody

I make too much money for free or low cost legal assistance, but barely make enough money to get by. I don't make enough money to come up with a retainer for a lawyer and I need one now. I need a lawyer who will accept a retainer in the form of monthly payments of about $500 a month, possibly more once my child support gets reinstated. Their father has been physically and emotionally abusive to my children. I deparately want to protect them. Where can someone in my situation turn? I don't have anyone who can loan me the money and since my separation my credit has taken a real hit, so getting a loan is probably not an option. Thank you.