Hi /sci/, how do I cope being a midwit?

I am a grad student who worked my butt off to get into grad school. Before grad school I was pretty confident about my capabilities and weaknesses, I knew I was good at some things and bad at others. But grad school fucked me up. For the first time in my life I witnessed the difference between a midwit and high IQ, and I was absolutely blown by it. I fought it, struggled with it, finally came accept it but I still cannot recover from it. I wasted my last three years obsessing over it, wasting time arguing with people over it, and sometime just giving up on myself. As a result, my performance has been relatively poor so far. My PI has been giving signals about it, but thankfully has not taken any decision based on it.

I want to fix this before it breaks me permanently. I need a good, healthy coping strategy. Help this midwit /sci/.