Have had this happen but with the longer version, so the inclusive angle was slightly less.
A "Pro" painter did the poor packing job for me.
I had sent him reusable box and packing that must have gone elsewhere... Grumble- especially as he commented it was the best packed frame he had ever received...
Big Big flat screwdriver, inset parallel to how the axle would go, open it just a bit.
back out adjuster.
thread adjuster in from the back end till it terminated just short of the "slot".
3/8" fine thread bolt at U, with as stout of machined washers as you can find- tighten up- you want to keep the metal from bulging more.
Some heat, not enough to burn the paint or chrome, but even 300 °F will help,
slowly using that big flat screwdriver twist it in the opening to open it up. You want to walk up to the amount needed, not beyond.
Take things apart and check flatness
install wheel and check derailleur hangar.
50/50 the chrome will pop loose.