Thoughts like the ones you're talking about just spin around in my head. The only way I've found to lessen them is to get them out into the world, either by journaling as people have suggested, or by simply talking with someone about it.
Saying something like "I'm really mad at _______, and I can't understand why I was treated this way. It's not fair"... to a sponsor, friend, or sibling, is a great way of simply 'airing those feelings out' and getting them into the sunlight.
Don't keep them bottled up inside of you. Thanks for the post. I know where you're coming from.