That bolt that you broke is a stud and is threaded into the fork. It must be extracted. Can't see yours, but there are many ways to extract a broken bolt. Drill a hole DEAD CENTRE in the stud and use a screw extractor. A very small amt. of heat and some good penetrating fluid (not wd40, cause it sucks).
If you are not into this type a thing I highly recomend having a machine shop remove it for you. On mine I installed "heli coil"'s to each hole.This makes each hole steel threaded, instead of easilly damaged. A machine shop can do this for you.