I, for one, hope that you'll post back on this, because I don't think that the responses that you got adequately reflect how huge, volatile and contemporary this area of law is. The fact of the matter is that NYMinute may be correct, but the law is unsettled and contradictory decisions abound.
The snide dismissal by Ohreallynow? of the Haines case cited by Kanchazi reflects a total ignorance of the issues and a waste of bandwidth. While what we have is not the best summary of that action (which, incidentally, was a California case) Haines was formative, because it galvanized actions by credit card issuers, banks and any entity engaged in wire transfers to make what efforts they could to be "non-participants" in Internet gambling. Entities such as Visa, Mastercard and PayPal now refuse to process transactions.
Just a very small number of points:
Since that particular summary was written, Congress has overwhelmingly passed the Internet Gambling Prohibition Act and sent it to the Senate.
The Dept of Justice did and continues to consider any form of Internet gambling to be illegal, based on the existing Wire Act, but, in another formative case, a federal judge in New Orleans held to the contrary and found that it was only applicable to sports betting.
The US is at odds with the rest of the world in that, despite the Department of Justice, the World Trade Organization has ruled that the US "must not block gambling sites overseas". Extension of US policy could subject it to WTO sanctions.
But let's take the issues from macrocosmic to microcosmic and look at your case. You say that gambling is illegal in California. I'll skip the easy targets like the Indian casinos, the card clubs in Gardena and the California lottery. California lists 11 named games, including "21" and any "banking or percentage game" as illegal. The Penal Code proscribes sport betting. But other wagers are not specifically proscribed. On that basis, one could argue that it's not illegal to play poker for money. Your shield may not be as big as you think it is.
Then, there's the way that you "bought in". A number of courts have held an EFT transaction to be the equivalent of a transaction by check in various instances. If you had gone to Las Vegas and done the same thing, there is no question under present law that you could not be sued for your gambling debt in California but, issuance of a "stop pay" instrument, absent a valid dispute, is a "per se" violation of Calif. Civil Code §1719. It subjects you to liability for the amount of the check and treble damages of $1,500 per instrument, if the recipiemt fully complies with the Code section. And, where you committed the act, in Las Vegas, gambling would be legal and you'd be toast in California later on. You could be sued on that basis.
Personally, I think that the reason that NYMinute's friends walked is not because the creditor was out of the country (that's no necessary deterent) but because the creditor didn't want to "test the waters" on a single small case, when the environment is foggy and a multi-billion dollar, world-wide industry is involved.
Hope you're as fortunate, because there is no question that you were morally wrong. It just remains to be seen if someone will test whether you were legally wrong as well.