Readying doesn't interrupt anymore - you get hit by the Sneak Attack and then get to counterattack.
Also, keep in mind that unless you move (which carries a penalty to Stealth if it's more than two squares) they know what square you're in and can attack it at a -5 penalty (or no penalty at all if it's a Close or Area attack).
Also, keep in mind that unless you move (which carries a penalty to Stealth if it's more than two squares) they know what square you're in and can attack it at a -5 penalty (or no penalty at all if it's a Close or Area attack).