Sorry, but no one here, nor Apple can help you with this. Once you deactivated Find My, the phone become unlocked and the thief can now do anything they want with it.
Your only options, at this point are:
- Change your Apple ID's password.
- Contact your cellular carrier and report the phone as stolen. They can work with the IMEI number to "blacklist" the phone so that it will not be able to connect to any cellular network.
- Contact law enforcement, if you haven't already, to report it stolen ... and assist them with the details of the robbery.