What philosophers have specifically explored failure and the fear of failure? What works / passages?
Kierkegaard addresses the idea of this type of disconcerting failure under the concept of vertigo through the pseudonymous works Concept of Anxiety by Vigilius Haufniensis and Philosophical Fragments by Johannes Climacus. In both cases, this disorientation is a sign of the dialectical problem of taking your bearings from an inadequate source -- a theme more completely considered by his pseudonym Sickness unto Death by Johannes Anti-Cliamcus.
For Aristotle, lack of confidence is a type of vicious character. The Greeks unlike us though hubris or something near to it was a virtue of the magnanimous man alongside the right forms of hospitality and justice.
For Sartre, this is being situated by another and should be overcome by one's own bold assertion.
If you can give more contours to the emotion, then it would be easier to narrow which philosophers are meaningful to your issue.
Miyamoto Musashi's book of five rings, D.T Suzuki's: An Introduction to Zen Buddhism, and Yamamoto Tsunetomo's Hagakure are all excellent work, and there are many more excellent japanese works but these are my favourite. They all explore the idea of performing under a looming threat of death, and give strategies for overcoming fear.
Nassim Taleb writes about the topic of failure in the book Antifragile. He looks at how things are made worse by failure (think of a glass falling on brick), but some are strengthened (an example he gives when interviewed is how forest fires clear dead vegetation making way for new trees and bushes to grow in).
Taleb has been interviewed several times on EconTalk, where he discusses some of these ideas about failures and how individuals and governments respond to failures and mistakes.