Order new one. Looks like it caused delamination. You probably did this but check your transoms to make sure you didn't damage the transom itself or the pintles/gudgeons. If you ask a professional I think they might suggest a new rudder.
While waiting for new one grind out the leading edge and figure out how much delamination is going on. If possible, squeeze epoxy into rudder. Clamp. When dry lay up couple layers of glass over the leading edge. Use as backup rudder. That would be my plan but I like working on stuff like that.
If you are big into racing I would do that (and if you have $ for new rudder). If you sail recreationally then you can try the repair.