Sometimes the devil will mess with you, so keep this in mind...
It's fine to look back sometimes, to remember what's worth remembering, and to learn some things from experience. But the grand majority of looking back is counter-productive.
We've got to be able to move forward with our lives. Carry on with the good stuff you've accumulated if you can, but drop the baggage so you can move free! There is nowhere to go but forward! It may sound like a cliche, but if you let something from the past haunt you and if you let your fears control you, you'll be paralyzed.
But its' the wounds, especially those of rejection and neglect that are especially hard to forget. Nonetheless, you have to. You have to forgive. You have to move past it and stop dwelling on it and you have to recognize that if pictures of instances of your dissapointments keep on popping into your mind....it just may be the enemy trying to mess with you. And you need to resist him. And you need to follow God who tells us in His Word that we should forget those things which are behind and press on towards the mark of the high calling of Christ.
People are going to hurt you. They're going to hurt you so badly! Like the twisting of a knife. You're going to know some Judases. That's life. It isn't fair. And if you have a good heart, you'll probably never be able to understand the cruelty and lack of empathy, but it exists for whatever reason...but if you don't let them, you don't have to let them destroy you. I've been used, misused and abused sometimes. And will probably be treated to it again sometime, but ya know, if I just lay it all at the feet of the Only Real Judge of all the Earth, who suffered wrongfully a heck of a lot more than I have, than I am free from having to obsess about it. I don't have to defend myself.