I rarely have an issue with this for some reason. Trying to remember what my settings are.

I think I use auto-facetarget as healer, but I never die to it. How does it cause your death? Generally, once I start casting a heal, it won't cut me off, even if someone goes behind me. Or maybe it does and I just never have that issue due to my own positioning. When I cast Stone, it will cut me off if the target goes behind me, but smart positioning can prevent that.

If you mean dying to face-away gaze attacks or directional attacks like Headwind/Tailwind, just make sure to stop before that. Also, slide-casting is a critical skill for any caster player. And once your spell is in the slide-cast window, you can safely turn around and you'll cast the spell while facing the wrong way, without turning around. Same goes for Cures. You can also use these windows to reapply instant casts like Regen.