I also have an "incurable" illness (chronic fatigue syndrome) that led me into a similar dark place as you describe. But I also have found great hope and understanding from this low ebb. I found the part of myself beyond my intellect that I see now is the true core of who and what I am. I could see that all of my negative thoughts and feelings were just that, thoughts and feelings, and that "I" or the real me, was the one who had the choice to believe these thoughts and feelings or not. As soon as I freed myself from the viscous cycle of negative thoughts and feelings, my health began to turn around and has constantly improved ever since tis moment. It is from this place that I find it much easier to see the "things we don't know", when we are not fixated on how uncomfortable we feel not knowing.
Hope you find relief from your condition, and answers to the "unknowns" in your life.