Above a certain size, Windows does not give fat32 as an option. You MUST use a 3rd party tool to format.
FIRST: Copy your entire sd card to your computer.
Do you have a hidden partition emuemmc? Or is it file-based? if it is file-based, you're good. If it's a hidden partition, you need to backup your emuemmc with nyx. (just to be safe. In theory, a regular format will not touch the hidden partition). Copy that backup to your PC as well.
THEN: Format your card in NYX (hekate).
Copy all of your files back onto the card.
Optionally, you can format in Windows using something like mini tool partition wizard. But NYX is recommended.
I've said it before, and I'll say it again. The option to install exfat drivers or not is completely RETARDED. It should always be installed. Installing the drivers does NOT mean that you HAVE TO use exfat. So what harm is there in installing it? None. Absolutely none.