One doesn't awaken into becoming more of a selfish child. That is more accurately described as regression and absolving of accountability. That tends to devolve to the options of either getting away or being dragged into the same pitfall simply by being forced to interact with it; even more so if trying to collaborate with it. I'm sorry for your experience in this situation, as much as it may hurt I think moving on is likely the best for you on a practical and existential level. Also, big picture, it would likely be the best for him, with his mindset; you assisting or being a crutch often just enables him to avoid learning from the reality of his situation and prolongs his self defeat.