Can it be welded and/or reinforced with another piece of steel behind the part that broke off? I am basing the idea on what your photos seem to reveal, and it looks "doable.? Even a simple arc weld on the rear of the cracks might be all right, but adding another piece of steel behind the broken part would allow one to reinforce the part that broke off and, in turn, allow the reinforcement piece to be welded to the slotted section, doubling its original strength.