You may be able to get the court to order your son to stay with you, when you go to court on Tuesday. From what you've said, your son is on board with the move. The juvenile court has complete control over where he lives. You could also mention at that time that you need to continue to get your, your son's, and necessary household items out of the house without interference. And the court might specifically order that, too (it's worth a try). The juvenile court is all about providing a stable home for the juveniles under supervision.
If you do go back to pick stuff up, I'd call the local police to have an officer stand by to make sure there are no problems.
Dang, sorry things took a turn, but glad you are keeping your cool. You're right, it will all work out in the end.