Can someone help with tips for court custody of my children?

My ex husband wants to get full custody of my sons which is 3 and 4 right now we are 50/50 and my oldest will be starting school next year but i know that he wont be caring for them his mother will he has no place of his own and cant even take my 4 year old to preschool or pick himup his mother does and she handles all the business with his school. he has mental disorder that requires medicine to control his anger which i dont even know he taken right now anyone got tips for me to get my boys i cant afford a lawyer i wish i could