my mother and father have primary custody of my neice and nephew. My sister doesn't want much to do with them and their father isn't a great influence but does keep up with visitation but no child support (he doesn't keep a job either) The children dread going with their father and it's really hard fro my parents to let them go.
They come home with all sorts of bumps and bruises. Their father doesn't hit them or anything, he just doesn't pay attention and is on and off drugs all the time. My mother records EVERYTHING. She emails it to herself so there is a time stamp on the message just in case she has to use it in court.
If you think the child is in danger and you have proof, you need to keep really good records.
Seeing a therapist might not hurt either. It helps my mom to feel like she is doing something (journaling and telling someone else)
I hope this does get better. If it helps, kids often cry for their "Stable" parents but stop soon after they are out of sight. My son knows I'm coming back when I drop him off at preschool or sunday school, but it doesn't keep him from screaming. He's usually over it by the time I get to the end of the hall....doesn't make it hurt less for me though. Hang in there and give it over to the One who can do soemthing about it