Darkness comes. In the middle of it, the future looks blank. The temptation to quit is huge. Don't. You are in good company... You will argue with yourself that there is no way forward. But with God, nothing is impossible. He has more ropes and ladders and tunnels out of pits than you can conceive. Wait. Pray without ceasing. Hope
I really believe that all of us have a lot of darkness in our souls. Anger, rage, fear, sadness. I don't think that's only reserved for people who have horrible upbringings. I think it really exists and is part of the human condition. I think in the course of your life you figure out ways to deal with that.
Light is meaningful only in relation to darkness, and truth presupposes error. It is these mingled opposites which people our life, which make it pungent, intoxicating. We only exist in terms of this conflict, in the zone where black and white clash.
From my point of view, God is the light that illuminates the darkness, even if it does not dissolve it, and a spark of divine light is within each of us.