I feel your pain - I thought I had finished my thesis in 2006... I got told I needed to re-write and edit bits of it... over a year later, I submitted... there was so much red pen, so many tears... I was so, so sick of it and if ANYONE asked me when I was going to be submitting, I bit their head off as I felt like such a failure as 'why couldn't I get it right and just be rid of the whole thing?'
Hang in there.. THIS is the hardest thing you'll ever have to go through and I bet you're on an emotional rollercoaster... you re-write and think it's better and then you get told you need to make more edits.. just keep going and think of the day you'll graduate.. sounds so petty, but every time you re-write it gets better and better....
Keep going, it will be worth it