SE has gotten a lot better about returning hijacked accounts so you should be okay. I've read of lots of people who got their passwords reset through Customer Service by being able to give the registration codes. If you still have them you might be able to do that over the phone rather than having to wait for their letter. I've heard it can take months doing it through their snail mail system.
"Life should NOT be a journey to the grave with the intention of arriving safely in an attractive and well preserved body, but rather to skid in sideways - Chardonnay in one hand - chocolate in the other - body thoroughly used up, totally worn out and screaming 'WOO HOO, What a Ride!"