I agree about leaving out the lawyer. It sounds like Starman would still like to have a relationship with the younger brother. If you go to court that is probably the end of that relationship. Maybe you could amend things by agreeing on a realistic payment that would help soften the financial blow while simultaneously restrenghening your relationship with your brother? Something like "Hey I know getting back that remaining 4,000 is probably not likely at this point but maybe we could agree on getting me 2,000 and just chalk it up as a lesson learned." Just a thought, but it all depends on how much you want or need that remaining money versus how much you value your relationship with your brother.
Regardless, I am sorry to hear about the situation you are in. It is harder than people think to turn down family members in need.