How do I get a pro bono divorce attorney?

We got married under Syariah court. I'm a legal resident, we have 3 kids together. Throughout our marriage he's on and off drugs, never held a job, we've been from home to home. I and my kids have been to a woman shelter. He's abusive with us. I and our kids have been given 5 years protective order. He can't be near us within 300 yards. I can't afford a divorce lawyer. He even threatened to take custody of the kids and will ask for spouse alimony and will request me to pay his 36,000 student loan since I'm the only one working and the main provider. I have a hard time trying to pay all the bills. I cant afford the 36,000 loan. I and all our 3 kids have been living separately from him for a year and 3 months. Under state law, can I get full custody since I promised our kids that I will not let bad things happen to them again. Will I have to pay him spouse support? I need a pro bono lawyer to help me, represent me.