I think actually every country- at least every country with a modern functioning financial system, which includes the UK or Slovenia, wherever they are located.

Replace Bitcoin with "Financial instrument" and I think that should give you an idea of what you've done. Maybe governments didn't CARE about bitcoin when it was worth a few dollars each, but they aren't obligated to enforce every law on the book, they are usually content just HAVING the law on the book, and now that Bitcoin is worth real money- I think every modern country in the world would view what you've done as money laundering.

So yeah, you're a criminal in the eye's of the financial regulators. Whether or not they go after you is up to them and whether or not they can find you. They CAN however find Bitstamp, so they have prudently seized your funds to play nice with the police if they ever show up. That said- technically unless you have a government ID with your 'Fake Name' you're pretty much screwed even if weren't illegal (which it most certainly is). If you registered as "Buttlick McBalls" Bitstamp is well within it's rights to ask for your government ID with said name on it.  From bitstamps point of view (not considering the criminal element), until Mr McBalls shows up, that money can very nicely pad their 'reserves' for a rainy day.

Good luck.