If it broke at the bend it is likely either too low of spoke tension or just poor quality spokes. The tension is easy to check with the right tools but even if you correct it chances are fatigue has set in and at the very least you should have the wheel rebuilt with quality spokes.

I will stand behind my comment about a properly built wheel should NEVER break a spoke, no matter how big/powerful you are outside of physical damage.

If you let us know where you are located we can help you find a good builder close or if you happen to be near Colorado Springs I can certainly check your current wheel out, I would not charge anything just to check it over. I build wheels for a living so I am pretty confident in my ability to tell you where the problem lies.