Another piece of advice, don't mix finances and "friends."

Simple. Stick to it. Don't waver,don't worry and don't for one second think your wrong.

Chances are he has already got himself into trouble with someone, because he was banking on you coughing up.
Which is why he is in a bad mood.

Best. Case scenario you only lose the money.
Worst case scenario you end up filing for bankruptcy, and wind up with a criminal record.