~snip~
I have one question am I a scammer too or did I do wrong by not sending him his Etherume back because after this incident my conscience has been beating me.
stay safe.
There is too little information about whether that person is a scammer. You need to try to find out more about him and his intentions. It is possible that he is not a scammer at all, and then it will be very sad if you don't return his money to him. If you have ever been deceived, then it is not for me to tell you how unpleasant it is.
Was at the office when a message pop on my Facebook messenger
Have you ever wondered why he contacted you? What were the prerequisites for this in your FB?