There comes a time where you casually lay back and reflect back upon moments in life. There are the ones that will be forever engraved into your memory and there are the ones that you hope to forget. However it's a mixture of those memories that shapes who you are. I often hear people say 'I wish I could just forget that happened'. I actually say that myself too. But have people actually thought there's the possibility that if they erase that particular memory, you wouldn't learn from it? Just generally, you learn or act against the cause of a bad situation or memory right? Therefore the negative events are not necessarily bad experiences in life - you just have to be more optimistic in thinking that what's done is done and there's no other way than to learn from the mistakes.
A classic example would be a couple breaking up and the victim feels wronged and is constantly sulking/blaming the person who called it off. In all seriousness, you just have to learn from that. Not to commit the same mistake again in the relationship or not to do or say something.
It can be a situation where you find out a friend has been lying to you the entire time so next time you would not trust people that easily or maybe you will just avoid people like that.
The point I'm trying to highlight is that whatever happens to you in life just stays with you. No matter how hard you attempt to distract or distance yourself away from the negativity, the more it haunts you. Even though it might be something that's drastically off-the-chart-horrible there's always that positive light to it.
Although people often say focus on the positive things in life, I reckon we should embrace the positivity and negativity which ultimately shapes who we are.