Awww chick, I'm so sorry to hear that
. Big *hugs* coming your way!
All I can say, and I know it will be no comfort whatsoever, is that you will come out the other end, and you will be fine. I know it's scary being alone, I really do - but you might just find it's the best thing that ever happened to you.
My fiancee broke off our 2 year engagement and 6 year relationship the week before Christmas last year, and it ripped me apart - I felt exactly the same as you do. However, I've now moved into my own little house, and I'm stronger - and would you believe it happier - than ever.
Don't ever think you're not good enough, or you should have been slimmer for a guy. You have to do everything for you - not him, and if he really was the type of person to judge you on weight alone then was he really the person you want to be with?
I know it hurts right now, but the cliche is true - time really is a healer, and in 6 months you really will look back and realise it was all for the best.
Sending you lots of love
xxx