Mikey, that sounded really awful, sorry to hear that.
I wasn't ever really suicidal, just desperate. Like Russ, my concentration was really poor, had to read and reread things to understand anything, my thoughts were wandering like a drunkard. I was always anxious and panicky when I needed to have some presentation or a talk, this must be a classic. Had also a hard time to relax, was always under a stress, and even small problems seemed overwhelming. In the end I was so tired and depressed that nothing mattered much more, felt like a zombie, but just kept going.