I am not the best to tell you...
0) I would do a sysnand backup with hekate, yes, ANOTHER one, but still save the one you already have. This is in order to have it in case you wan't to go back to the current state, god knows what for, but yeah, do that and keep it. Also, save all data partition files to some safe place too. It could be the case the saves are still there somewhere ( at least save the nintendo/emutendo/... whatever reinx uses for that, folder ) and could be extracted. You may also want to run lockpick and save your /switch/prod.keys and switch/title.keys if you don't have them already. These will work for decryting nand images and maybe extracting saves.
00) see the hekate+atmosphere howto guide, there's various guides, maybe a youtube video or so...
a) you have a full nand backup, right ?
b) in the current state of the SD card, do you have an emunand/emuMMC partition ? if so, you can restore your nand backup TO THE EMUNAND partition ( just don't touch sysnand, just don't; yes, I know it isn't necessarily a risk, but you don't need to do that so don't ). If you don't have that, repartition the SD and create an emuMMC partition, leave it at 29GB size ( just tap in the middle of the slider, do not slide, tap, and make sure it says 29GB ).
c) once you restore your nand backup to the emunand, enable emunand ( it will probably get autoenabled, but still )
d) boot CFW ( by default, with enabled emunand, it will use the emunand )
*) install Checkpoint and save all game saves, then copy /switch/checkpoint/saves folder to a safe place so the next time you will have the saves to restore everything.
Please, take note here, I am not responsible for anything that may go wrong ( with a nand backup and only restoring to emunand, you won't go worse ).
Good luck and good Valentine's Day