Custody

Anyone a attorney or lawyer or gone through the whole custody thing my son is 9 months old my husband and i take care of him I love him he is my everything i left his father a month into my pregnancy due to cheating drugs/alcohol and verbal abuse he has wanted no part in my sons life even said it many times I've told him I wouldn't keep him from seeing him I was in the hospital for 2 months with him he was a preemie the county told me to do a DNA test so I did I regret it now but anyway DNA came back and he's his of course and now he's saying he wants full custody after 9 months of refusing to see him what do I do I'm in NY