You will find that you don’t have to labor so long under the weight of the thoughts that are driving the pain.
Inquiry will show you the other side of the story in a way that takes care of them ‘for GOOD’ (both in a lasting way–like seeing a snake in the grass then realizing it is just a rope so you can never believe it is a snake again–and in a way that always moves in the direction of the greater common good–more compassion for self and others).
Another important chapter about undoing regret: Seeing that it ‘should have’ happened–because it did. There is no other reality.
And realizing that it’s just you trying to evolve yourself past the oh-so-human (but oh-so-painful) belief that you can ever know what would have been better.