PS, if she's not doing well in her new home, then you both have nothing to lose by bringing her back except for possible disease introduction. That is your call - you could quarantine her away from your new ones for 30 days to be on the safe side.
Sorry for your loss. It has happened to me and it's pretty traumatic.
I think you should take your time to decide. You've been through a lot and it seems that you don't really need to decide anything right now other than knowing you'll get more chickens eventually - of course . It is great...