Just got scammed out of my subzero, what are the ways to best report this player to warn other players?

I play on Xbox and it happened this morning. I can give more details of how the scam happened upon request. I understand this is my mistake, and I should be more careful in the future, however I'd like to take all appropriate action possible. Thank you for your help.

Edit: What happened: I joined an Xbox live friend to play 3's and he was already partied with someone from the EU. I was going to trade with the guy from the EU but i kept getting "player unavailable" likely because I am US West and he was EU. My Xbox live friend was US East, and could trade with both us, so we used him as a middle man. I was dumb and trusted him with my shit, so as soon as I gave it to him he left the party and blocked me. We had played off and on for about 6 months so I was dumb and figured I could trust him. The EU guy was shocked as well, so I don't think he was in on it.