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.

[Valyndris]

It should be fine after only 3 days in the fridge, when I feed my ball python I skip the refrigerator process. I just take a rat out at around 12pm and by 7pm to 9pm it's thawed and good to warm up for 10 mins in hot water and ready to be fed to the snake. He's an adult ball python and eats medium rats, smaller rats take a lot less long to thaw so you would be able to take it out later depending on the size of the rat. I remember when my ball python was just a baby I only had to take rats out about 2 hours before feeding him. That's just my method, thawing slowly in the fridge is just as good.