The enemy likes nothing more than having you relive your past sins and feeling worse and worse because of it. I’ve been there many times. You need to remind yourself that yes, you are the child of the one true King and He took our sins to the cross. They are in the past. They are done and you are forgiven.
I found this awesome blog from Mark Merrill to help you out of the pit when you can’t forgive yourself and I hope you’ll share it with others.