How thick is it in the handle area where it broke? Can you take a side view picture of the handle and dip area?
I think I would have put a piece of osage on the belly side of the handle, from dip to dip, to strengthen that area and keep it from bending.
Actually, I would have either used walnut OR red cedar for the center lam, and then osage for the belly lam, THEN built the handle up further with osage that extended from dip to dip. At the center of the handle, I like it to be 1 1/2" thick.