You should drive your car slowly to a welding shop and remove the wheel and have them weld on the broken stud. Getting the broken stud cherry red and letting it cool, will shrink the bolt, and it can then be removed by haviing them weld a nut to the broken stud. The part needs to cool by itself to shrink. Do not quench the part with water or oil or anything else trying to hasten the process. You'll just defeat yourself in the task.
You can position a nut over the broken stud and weld through the hole in the nut to the stud.