how could Eddie work to self-improve and undo the damage caused by his father? What does Eddie need to feel healed and whole again?

I think this is really asking for your opinion. I think Eddie really had to work hard to let go of his past. He had to somehow separate or at least reconcile with his pain from his past. Instead Eddie internalised his pain and carried it with him into his adult life. Eddie needs to accept what has happened to him and embrace his identity separated from his past.