Blydesigner Jason Bulmahn har sagt :
The wording was intentionally put together to specify "at the end of your turn". That is the moment when you check your status to see if you can maintain Stealth. This does allow you to move from cover, use Stealth to approach a target, and make a single attack, at which point, Stealth is broken, regardless of the outcome. Now, if you slay that target with one hit, and still could maintain Stealth from all other foes in the area (if say, it is dark and they cannot see you), a GM might reasonably interpret that you could maintain Stealth from other foes, but that requires GM interpretation and is not really the point of this particular situation.