Regardless of your efforts, stress and losses are an inescapable part of life and chess. Because of this, chess helps us effectively train to deal with the challenges we face in life. However, sometimes all that can be done is to seek to learn from mistakes and try to find meaning in disappointing experiences. For the most painful experiences, try to learn about personal limitations/capabilities as well as gain compassion for others who are suffering in similar or more extreme situations. You are not alone in your experience and unlike chess, overthinking your position will cause more harm than good.