I have seen a couple of them break in exactly the same place was it on the riders left where the mounting tab meets the main part.
Try "RapiFix" available at AutoPro and most auto accessory shops it is a powder and a liquid it ia super strong and wont need any plating or reinforcement, working on the back out of the bracket line up the broken piece and simply put a drop on the two surfaces, hold together .. put some powder on the joint and put another drop apply some more powder till built up a little sets rock hard in seconds