Ok, I'm guessing moneymart is some sort of dodgy instant payment check cashing place and that's why they needed contact info. Why didn't you just deposit it into your bank account and wait the few days for it to clear?
As far as the money order being fraudulent, it sounds like they've talked you into believing that you've fallen for a scam, rather than
physically examining the MO without prejudice and concluding it's fake.
So what are we left with?
- A valid money order that you voided yourself
- One pissed off model/webmaster
- This entertaining thread