So how long do rats last in the fridge?

[Bogertophis]

I'm not sure. But had some in the freezer in plastic bags, and got to the last bag, and it was nothing but "exploded" frozen blood. So, it must be less than two months. But, since I have three out of four that are way too picky, I feed live now.

Sounds like maybe they defrosted, spoiled & were refrozen? Rats (or mice) do not simply "explode frozen blood" while in the "freezer" (assuming it's cold enough).
And certainly not in 2 months time being frozen. For the sake of your own health, you might check how cold your freezer & fridge are, so food isn't spoiling. It's also
possible that you had a power outage while away for a while. There's ways to test that.