I say that if you are telling the truth and there are 3 pending child neglect cases on the ex, then your chances of getting child custody are pretty high, considering the fact that you are suited to have the children in your custody.
I have had friends who constantly had to fight with Child Protection to have the children taken out of a "bad" situation (abuse, neglect, unmoral conduct). I say never rely on child protection to step in.
Need proof, look into a pending legal case in Cincinnati in which a mentally challenged child in a foster home was wrapped up in blankets, forced into a closet and left there for 2 days. The child didn't have any food or water, desecrated himself, and died. The birth mother is suing the county on a wrongful death suit (the child was taken from her along with three others because of willful neglect). The foster parents are charged with murder, neglect, and other charges as well.
Get yourself an attorney and FIGHT!!!! I'm sure that you can get custody if you can prove to the court that you are fit to have custody, haven't had any reports of abuse, neglect, etc., and have the means necessary for proper care. Good luck!!!!