How bad did I screw up

Two of the three bolts would hold it. That part of the block is very rigid & so is the mating section of the pump housing. I would see if the damaged hole can be tapped any deeper within the current hole depth, even if just 2-3 threads. Then use a stud, loctited in place, just snugged up; it becomes a 'helper', not the main source of attachment.