Don't torture yourself over the past. Use it as a teacher. Whatever happened to you in the past has only prepared you for now. We all need to learn and not burn from our past. Satan wants us to focus on what we have done wrong, when God is saying let's move on to what is right. God keeps us moving forward to continually grow. Whereas, if we are thinking about our past, we are sitting still and sometimes going backward. That's Satan's plan, stop growing, stop knowing (who you are in Christ)! (Ephesians 4:31-32-"Get rid of all bitterness, rage and anger, brawling and slander, along with every form of malice. 32 Be kind and compassionate to one another, forgiving each other, just as in Christ God forgave you.") The Good News is God has forgiven you, so you must forgive yourself!
We seem to always lean on God more when we are in a valley. I think that is where most lessons are learned for the simple fact, because we feel like the situation is out of our hands. We find ourselves crying out to God in desperation to fix our lives. When truthfully, we may have to go through some pain to learn the lesson. Our Father in Heaven wants what is best for us, and if we are His, and we step off the beaten path of God's Will, He is kind enough to get us back on track. So, instead of fighting God during times of learning, we should grasp a hold of His Hand and meditate on His Word. That is the only way we will find true peace. (Jeremiah 29:12-"Then you will call on me and come and pray to me, and I will listen to you.")