It’s really hard to understand Tofugu's way of thinking.
I'm struggling under intense pressure from Koichi, who aided and abetted me in a crime.
I’m just thinking about your new wife at home. Okay? Do you really want to make her suffer from your death for the rest of her life? So, don’t commit suicide.
You learned the word 苦しい (hopefully) in level 9. That word means suffering. So, if you make that into a verb version, you have to suffer.
The reading comes from 苦しい, so as long as you're on top of that word, this word should be readable for you as well.