I wrote down a huge section of that book, so I could share the quotations that helped provide validation for my thoughts, but I can't find them now and I don't own the book yet, so I'll go from memory.
At the end of the book, Charlie reveals something to the reader, which I won't get into here, and I'm sorry if this is a spoiler. He has to decide how to internalize the situation.
Charlie decides to forgive.
The character explains that everyone in the world faces difficulties, and it isn't fair to judge who's problem is worse, because to each person, that obstacle is gigantic. He explains he will never tell his children that people in China have it worse, because what they are going through at that moment is important to them.
What defines us, isn't the bad thing that happens.... although it can if we let it.
The problem with letting bad things overwhelm us and define us is that ... it keeps the cycle of hurt going. When we are hurt, our pain causes us to hurt other people, whether intentionally or not. If we are withdrawn, people feel hurt that we don't care enough to let them in. If we are aggressive, the aggression lets us steam roll over other people's feelings. I'm making the issues abstract here, but I think you see where I'm going with this.
Bad things happen to us... often because of those closest to us.
But we can choose to accept that those people were hurt at some point and that is likely the reason they hurt us. Does this mean we should hate them? Or realize that despite what they did, they gave us two presents for our birthday (in Charlie's case) or showed us how to draw a 3D pop can (in my case) - they may have done bad things, but there could be good memories in there too? Does this mean however, we let them into our lives despite everything? That's for the individual to decide.
But the only way to stop the cycle of hurt, is to stop being hurt.
Except the bad things as part of life, but realize YOU ARE NOT THE BAD THINGS.
YOU DON'T HAVE TO BE DEFINED BY THE BAD THINGS.
YOU ARE YOU! YOU ARE BEAUTIFUL! LIFE CAN BE BEAUTIFUL!
Be who you are right now.
Don't worry about what's back, or even what's forward. This moment, this VERY MOMENT, is real.