Originally posted by arimage RESOLUTION: Apparently I just wasn't twisting with the right amount of force.........
Just to make sure: Note that under normal circumstances unmounting a lens is as easy as mounting. No excessive force is necessary.
You should not mount the lens again, until you have found a solution for its offending pin. Either you can make it retract with the aperture ring or you can remove it.
Do not keep forcing it off, it might wear down the screwdrive hole in your camera's mount after sufficiently many tries. The mount is very sturdy but not designed to deal with pins like that one on your lens.