Thank you for the link to the book (สิ่งที่เรียกว่ากิเลส และวิธีทำให้สิ้นไป).

May I comment on “your last paragraph” (in the post)? Letting things go (ปล่อยวาง; ‘let it be’; ‘que sera’;..) may done in 2 ways: one way is with these สติ สัมปชัญญะ ปัญญา และสมาธิ (that is with understanding of the true nature of things) and another is with an Occam razor or a decision not to dwell on things.

We all at one time or another use one of these ways. Which way we choose may depends on our (conceited) knowledge or facts we have.