If you've rounded a number of nipples, I'd replace them one at a time, then as far as the wheel knows, it's no worse then snapping a single spoke. If you undo them all at once, you'll stay pullling the wheel about in directions it doesn't want to do.
However, if you've caused that much "wobble!" from an impact, I'd question whether it's a bend in the rim. Still, if it were my wheel, I'd try and pull it back and then keep an eye on it. If I start suffering looses spokes, it will be because you've had to use uneven tension to force it straight. If it works though, jobs a good'un!
Not a fan of spoke fixing agents either for just this reason.