Hey folks. Been reading a lot on here and elsewhere on the web as I explore insulating my basement. 

For background:
I’m in zone 4 but about 500 feet away from zone 5. (In NJ)
I have cinderblock walls in my basement.
2 ft of the wall is above grade, 6 feet below.
Soil is largely very, very low permeability clay.
house was built in the early 50s. 1.5 story cape cod.
House has no drainage systems on the interior or exterior. We added sump pit and pump last year when we got flooded from a storm.

Everything online says if you can, insulate from the exterior. For me that’s basically impossible due in part to cost of having someone dig out to the footings, and in other part to the house being surrounded on 2 sides by concrete (which I guess is also just a cost issue).

I was going to DIY foamboard (polyiso) on the interior walls, then a treated wood 2×4 wall assembly of rock wool. Then covered with drywall. But the more I read the more I’m worried about freeze and thaw issues with the cinderblocks no longer receding the heat from the inside of the house anymore.

Please convince me I don’t have anything to worry about, or if I do have some to worry about point me in the right direction for pivoting to correct. 

Thank you.