In so sorry you are dealing with this - Merry effing Christmas :-(
To ease your mind perhaps you could call the rehab center and ask if they would turn him away if he walks back in there. There's a difference between nowhere to go and nowhere you want to go. If they say he can go there then he next call will be easier - he can go back to the rehab center. Sure seems implausible that he wanted to stay and try shoved him OU the door.
As a parent I ache for you but I pray to God that I would do exactly what you did.
Praying for you,