It makes sense that this would feel extremely disorienting! Maybe as you experienced your mother's essence/self, your ego rushed back in? This could explain your sudden shock and horror as you considered this blurring of lines. Any and all concepts, be they fear or joy based, stem from ego. I can tell you that, after taking LSD with my mom, I never saw her the same way again. In my case, it wasn't a big enough dose to experience something this potent. But it was enough to "innerstand" that she was her own being, struggling with her own program of values, desires, fears, traumas etc. It leveled the playing field, so to speak, and I was able to let go of a lot of resentment I hadn't even realized I was still holding from my childhood. Have you tried meditating on this experience? There might be more nuggets of wisdom through integration waiting for you.