25 has given you some great advice. Keep working at this and dig deeper for personal strength for you and your kids. They need you to be strong and show them things will be okay. When you're feeling overwhelmed just stop and breathe. This will work out. No judge will separate your kids like your w is trying to do, but you have to keep working to keep them together and minimize the damage.
Be sure to be documenting all this (your efforts to get S back, his and her behavior when seeing you, how he looked) for your records. It is hard to remember when so much is happening and will be important for your case.
Please take care of your kids and yourself, you will get through this!
