since the stem is now broken, you can get rough with it and not worry about it.
and I think I understand that you broke the wedge free already
some suggestions:
Secure the fork in a vise or something so that the forks won't move even a little bit
hit it with a bfh hammer to break it loose
- or -
borrow the biggest pipe wrench you can find, and get a piece of pipe to use as a "cheater" to extend the handle.
twist to break it loose.
still no move?, get a propane torch and put some heat on it, try again.
once it turns you can get it out.