Happy Thoughts Never Come at 3a.m.

One week in and already I'm questioning myself about school. I have my first class (again, because I didn't finish it last year) for statistics tomorrow (since we started last week on Wednesday), and reading the textbook is only serving to remind me that stats make me want to shoot myself.
I still have two long-overdue essays from last semester. I've emailed one prof asking if he'd possibly still accept it and am waiting on a reply, and the other prof said he would, but told me the best I could possibly do in the course was a D. I should be grateful that he'll still grade it at all, and I am, but I'm feeling terribly discouraged as well.
That same prof, in the lecture for our first clinical psych class tonight (or last night, I guess...) was talking about the rigors of grad school, and the minimum 3.7GPA you need to get in, along with perfect GRE scores and research experience. Even as he talked about the work he was doing at the correctional center and the consulting and so much of what sounded fascinating and exciting to me, the hopelessness of ever getting there was reverberating in my mind.
I'm trying to remind myself that taking stats again is a blessing - an opportunity to correct the mistakes I made last time; that I'm blessed that Reid will accept the paper at all - a D is better than a Did Not Complete, which holds the same GPA value as an F.
But then I wonder if I should just scrap the whole thing - while I still can, and get (most) of the money back and give it back to the student loan bureau. Should I tackle the whole thing again in a few years as a "mature student"? Would I, could I be stronger? I wonder if I should run away to the Island and spend time with my grandparents while they're still around. Should I retreat to my mommy and let her help me get healthy - lose the weight that is more like a millstone around my neck than a number on a scale. I'm 24 years old - an adult, by any standard, and I should be able to keep my own act together. (There were many swear words omitted from that last sentence. I just wanted you to know.)
I know that a lot of this is my depression talking - and if it's not that it may just be the voice of the devil himself. ˆI'm stupid. I'll never succeed. I'm ugly inside and out. Worthless. Damn it, I know they're lies! But they're insidious ones, and the ones that roll around in my head at now 4am on a sleepless night, because rainbows and unicorns don't feature in the dark watches of the night.