How can i get my kids back home?

Ill try to make this short but i am at my wits end. I have legal custody of my 2 minor children. We live in Florida. My kids go to New York each summer to visit their father. This year they asked if they could stay for the school year and after much agony i decided that they could. Since I have made this decision, their father has had the children staying with his mother. I talk to my kids several times a day every day. Their father and his girlfriend were arrested for putting someone else perscrption pills in my sons drink. There is an active chilf protective services case regarding this. I have asked my ex to simply put the kids on a plane and send them home. He refused. I have spoken with the child protective services and they are backlogged and still figuring out what they are going to do with this. I have called the police in NY and they said that there is nothing that they can do. I asked if I go to new york will they go with me to the fathers house to get the kds if i have the custody papers and they said no, so did the sheriffs department. They said that i would basically have to go to new york and go to family court and get an order requesting that he give me my children. What is the point of having custody? Cant my ex be charged with custodial interference? The only thing that I want at this point is to get my kids back home where they are safe and it seems at this point that even though I have custody there is nothing that I can do. Does anyone know how I can get my kids back without snatching them in the middle of the night and traumatizing them or without the expense of goingto new york and running around in circles there? any help would be appreciated. I am out of options that is why i am asking on here! Thanks!