Should it be that hard to remove? Of course not!!! But sometimes they are.

Mine came off with a drift, but it was a clean 2007 with low miles.

DIY spanner is my suggestion for next step as well. I would take a cheap crescent wrench and drill a hole in each finger of it (hole facing upward if the wrench was laying on the table). Then hammer a short pin into the hole. Could use a #8 screw or whatever is small enough to fit into the notch on the nut. You can then use the crescent wrench adjuster to set the width you need.