Just in my opinion and in MY experience you did a courageous thing by calling CPS. You started the process. It sounds like it is going to be a long one.
I am wondering if the Ex Husband of your friend will go to a lawyer and file for temporary full custody of the kids while this CPS case is going on. He can even file for this without CPS case.
It sounds like you are a very caring person and did what you thought was best for those kids. Thank you.