This experience—when you look back on it in 20 years—will play very little part in how you view your life, and it certainly does not indicate failure at anything, really. That is one irrational part of the statement. None of this indicates failure. You are already at advanced levels, which means you're already doing better in classes than the majority of your peers.
You grow every day, but no one is invincible. I'm pretty sure what you intended with that was to say that you no longer feel invincible, but even that is irrational. You are vulnerable, just like everyone else, and your mindset should reflect that. You should not feel invincible, because then the inevitable hardships of life (like this one) will show you quite clearly that you are not.
If you would like to be the intelligent person you are, I think you should add some wisdom to all that knowledge by thinking about the following and then reassessing your mindset to accommodate:
Shit happens, even when you do everything right. If you feel invincible, then you are fooling yourself. You should strive for a growth mindset, not an invincibility mindset.
Really think about the worst that could happen with all of this, realistically. Think it through all the way, don't stop at not getting good placement at your choice of university. Keep going with the visualization of the future: what happens if you don't get a full scholarship to one of your choices of university, the so-called "good" universities? Don't catastrophize about it, really think about what you would do should that happen. I'm sure you'll find that you will be just fine and can still thrive, and that you still have plenty of options.
True courage and strength is about responding to adversity with grace and wisdom. If things didn't go wrong, there would be no courage to be had. If you want to excel at life—truly excel—then you can do that by handling scenarios well in which you don't get your first choice of outcome. Being wise really is more about how you walk the path than it is where the path leads. Figure out how you can handle this situation with the most courage, wisdom, and grace, and that would be impressive.
Your feelings are important, and it's important to acknowledge your feelings and know that it's okay to have them, but don't let them drive your thoughts or irrationality will result . Temper them with wisdom and truly assess the situation analytically.
Do not hinge your happiness on outcomes because you will inevitable be disappointed.
