So was it a simple tactical error that lost the game? In reality, my mental state was poor after failing to grasp what was needed in the position and handing the initiative and its accompanying pressure over to the opponent. The pressure of defending successfully (even if not optimally) eventually exhausted me and contributed substantially to the actual game-losing error. On the other hand, if I had stuck religiously to my thought process, using CCT would have prevented the loss. In the end, the result came from a combination of factors - tactical, strategic and psychological - as is the case with most chess games.
Even though I understand how the game evolved after analysis, it still makes me shake my head and wonder what exactly happened, especially after having a position that any English Opening player would love to see. At least the analytic process should help me play stronger in future such situations.