so, i just found out my comprehensive exam results - you can receive a fail, low pass, or pass. I received a low pass, but have to write a paper to submit to a conference. this is something new - not something I know that anyone else has had to do. It just seems like so much work - everything in my program has been so much work - seems like i don't do anything right - i've received good teaching evals, have had a couple papers accepted to a conference, but every step of the way, i always am given more work than my peers and I'm not sure if I should stay - it just seems like i'm finding out every step of the way by what they say that I'm not as strong as my peers - they tell me this. they say that i can learn, which is why i'm given the extra work. It just seems though that no matter what I do - there will always be something not good enough and that i might as well as save us all time and just end it all now. I'm confused and am not sure that I have the strength to keep on going with it.

Um...what? Me confused (no change there, then)..
Where are you (US/UK?), what are these comprehensive exams, what PhD are you doing, what is your issue and your third sentence is VERY long ;-)