Refrigerator side freezes everything even though it is set on the lowest setting.

Lowest setting is coldest, did you mean the highest temp?

Either the damper to the freezer is wide open or you need a new t-stat. If you change the t-stat make sure only the length of capillary tube is exposed that is exposed in the one in it now. Be very careful and coil up capillary tube and put behind t-stat without touching any electrical connections. Any sharp bend in cap tube will ruin it. I would get a universal t-stat at an HVAC or appliance parts house. They are $20 or less whereas one from the maker is $150 or more and they are made by the same people.