You should integrate this mod with Henkelmax's Corpse mod. So when you return to where you died. You can simply click on the corpse and re-inhabit your body and come back to life. But if the you take too long to get back to the corpse and it has decayed into a skeleton. Then you can't re-inhabit it. And you would be forced to possess a mob and come back the other way.

What is fabric and why not forge?

Fabric is an alternative modding toolchain made by the community. It is generally more permissive than Forge, which is very much welcome when working on a mod like Requiem.
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Sorry, this is simply impossible right now. There is an ongoing project that may eventually allow forge mods to run on Fabric, but it is not ready yet.

Is it possible to use fabric and forge together by putting their mods in different folders or this requires to edit launcher?

i know i'm a month late, but is there any way i can keep an eye on this project? it's nothing i've heard of or can find

You would keep an eye on this organization: https://github.com/PatchworkMC

It appears the mod you are suggesting is for Forge. If it is not for Fabric, it will be difficult to add compatibility for it in the near future.