Boiling acidity

I'm working like mad these days. And trying not to think about the future that is drawing closer and closer. I rewrite, transcribe and write brand new words on page after page, yet it never seems to end. I have started the final stretch and it is one filled with pain and constant doubt. Pain over not having time to see my friends or help the ex-husband around the house. Stress over if I have enough time, if I can finish this chapter in a week, stress that lives in the morning in the bottom of my gut then spreads by nightfall to my entire being. I feel I don't have time to do anything but sit my ass down in front of the pc in the office, yet I know I am the kind of person who needs some steam outlet! I want to go to the gym everyday, but feel guilty when I don't manage to make it there - it's a bloody 20-min walk there, and then 20-min back!! That means 2 hours at least out of productiveness at the office! or not... But I feel guilty for not going too, it is an evil circle of guilt, stress and stomach acid boiling constantly! I knew this moment would arrive - I knew I would get stressed and stuff, but I never thought I would start doubting my whole reason for doing this, doubting if now at the end I can actually do it - I have something to say, to add, to contribute? Every time I look at my past chapters I feel like crying, I feel I am not intelligent enough. That everything I have been doing for the past 4-5 years have been a waste. What am I contributing really? Am I meant to be an academic? I don't know...My brain is running on overload all the time, the beast is luring around every corner. The shadows are far from friendly. Yet I do not give up, I continue steadfast towards that day when it will leave my hands and Academia will judge me. Hopefully by then I won't have gone absolutely mad or put on 20 kilos!