Firstly, what you express indicates that you're a good person, and no human to date has been morally perfect.
I think you should change your overall attitude, or else I believe the same anxiety will continue manifesting itself in different forms according to your current thoughts.

In the recent past, I actually felt bad when realizing that I had not understood a topic sufficiently well.
Today, what matters to me is not how I've passed a course (for which I care), but instead whether I've actually understood the content.

And I think it helps if you affirm life; it you affirm life as something beautiful, sacred, worth of living, etc... then you may actually find yourself accepting the dark aspects altogether as well!