It took me awhile to understand and even longer to accept the fact that people change and that they aren't their past. It wasn't until I moved on from high school for me to understand that forgiveness is crucial for my own self-growth and life.
When I moved to college I met so many people, some of which turned out to become my closest friends. We all had history that the others didn't know about, but it wasn't super important for us to know. Their past didn't define them. I was more focused on learning about their current quirks, interests, and life. Not once did it cross my mind of how they used to be so I wondered why I had held the pasts and actions of those that I had once known against them?
Everyone grows up and does things that impact their lives. I am not the same person that I used to be and neither are the people that I used to know. We grow. We learn. We prosper. Time heals all pain and changes us for the better. I've learned that what one has done doesn't define them for the rest of their life. Life is all about growing and learning things about yourself as each day goes on. The journey may not be perfect, but with love and forgiveness we'll discover who we truly are.