Sorry about your scorpion. The poor thing looks like it's in a real mess. It looks like she may actually be a he, looking at the length of its tail.
I've never had to euthanize such a large scorpion, but given its size, crushing isn't a pleasant option.
I think putting him in the freezer is probably for the best. He could potentially last for weeks or more in this state before dying, which wouldn't be pleasant for the scorpion, or you.