Learn from your past
You've probably hear the saying, 'use the past as a springboard'. Develop a belief that any negative experience can be turned around. We can learn to change how we feel about most things in life.
For instance, if you get a bus home from work and it goes the longest way around until it reaches your street, you are not going to get on that one again, unless you like the scenery and the long journey.
You can't change what has happened. But you can catch the bus that goes the shortest way to your destination next time.
You can also learn to change how you feel about it now.
The past has gone and tomorrow is borrowed. Now is in this moment. Make changes in this moment. Use the past as a springboard.