Once we see that everything is impermanent and ungraspable and that we create a huge amount of suffering if we are attached to things staying the same, we realize that relaxing and letting go is a wiser way to live. Letting go does not mean not caring about things. It means caring about them in a flexible and wise way.
Letting go is not the same as aversion, struggling to get rid of something. We cannot genuinely let go of what we resist. What we resist and fear secretly follows us even as we push it away. To let go of fear or trauma, we need to acknowledge just how it is. We need to feel it fully and accept that it is so. It is as it is. Letting go begins with letting be.