Your comment about getting in touch with the greek police makes you look like a manchild who is out of touch with reality,
Maybe you missed the part where he implied killing my mother.
I'd hardly call it a death threat.
You are a fool. He has taken $50 from you. That is your fault. He has now also taken hours of your time, which you could have spent making money or doing something that is important to you. That is also your fault.
You now also look like an idiot to at least one potential customer. Again, your fault.
Why in God's name didn't you cut your losses at the fifty measly bucks?