@myheartbreaks4them,
I am so sorry for your situation. Sometimes whatever you do as a parent cannot change the decisions your child makes as they become an adult. I am happy though you have the children in your care. I was worried as, quite honestly, I wouldn't trust CPS to make the best decisions.
Could you hire a lawyer maybe to help you out with this? I'd be worried the mom may try to come take the children back and right now, legally it seems she has a right to do so. I am not sure what state you live in, but often times you could get reduced or free legal advice if you cannot afford it. I think it would be best if you get legal custody of the children.