I'm so proud and happy for you and the girl! You are lucky the state let you keep her being a single parent. Here in Tx it's extremely hard. My daughter's godmother's niece (whew-follow that connection) was abused by her mom's boyfriend and so the state wouldn't allow anyone in the family to take her.
I had to virtually fight to take her instead of her being placed in a overburdened house. The only objection they had, which they fought so hard over, was the fact that I'm a single, divorced mother. I got her and six months later she got to go back to her mother. But that's because Alina did what any mother would do-(she was in jail for the six months btw) she beat her boyfriend within an inch of his life while she waited for the cops to get there.
But I do have one piece of advice. Be very careful of the mother. Document everything that you can: how often she visits the father in jail, how she sticks up for him, ect. Some states hate to take away parental rights unless they have no choice.