Mad Men shows us that acceptance of the past -- not denial -- is what allows people to heal.  The scene where Betty confronts Don about his identity occurs in the dark, visualizing his secrecy and fear of being exposed. But once she unlocks Don's private desk drawer and pulls out his childhood photos, Betty brings his past into the light, and it's never fully hidden again. As the show goes on, Don's friendship with Anna Draper offers unconditional love and support, 
" I know everything about you. and I still love you."
And he begins to open himself up to other meaningful connections. After his divorce, he reveals his true identity early in new romantic relationships. Yet just admitting the literal truth of his past doesn't mean that he's honestly confronting the inadequacy and deceitful habits that he's developed to cope over the years. After he starts an appropriate relationship with Dr. Faye, it's not long before he dumps her for his secretary, Megan, and gives into old habits by cheating on her as well. He finally hits rock bottom when his daughter......
By season Seven, Don stops denying his history and torturing himself for things that can't be undone. As Don meditates in the last scene of the show, the warm sunlight mirrors his smile. Compared to the darkness when Betty confronted him about in season three, this light tells us that Don has found an inner peace that wasn't possible when everyone around him was in the dark about who he was. The identity crisis and the central question of the show "Who is Don Draper" is really an examination of  America's identity in the later part of the 20th century, and a call to action to us. Mad Men emphasizes that alcohol and sex, and old-school denial, can't heal trauma. The only way forward is acknowledging the past -- whether that's our personal past or shared cultural history. 
"I don't know if Don Draper can change, but I think that there is a point where the act of just admitting who you are is a big change."
Don's jurney is about more than admitting his real name is Dick Whitman -- because by the end of the show, he's not just Dick anymore, just like he's not only Don Draper. He's a true self-made man. When he calls the three most important women in his life in the series finale, he's reaching out for an honest connection that he once denied himself. And episode title, "Person to Person," tells us that Don is finally baring his true self to the people he loves. Don is implied to be the creator of the famous "Hilltop" Coca-Cola ad, and for the first time his creativity comes from a unified place, instead of longing and deep sadness. He's finally reconciled the suave Don Draper with the ashamed Dick Wittman. The result is advertising  at its best: hopeful, aspirational, painting a beautiful vision of the future that confirms there's hope for this new Don after all.