Wow Dez... I am sorry you are having a rough time.
I will stick my neck out there and say - don't leave.
Really, what you need to do is talk it out, and stop talking about the wedding - go on a date, have dinner, make a picnic in your living room, do what ever your budget will allow.
But the rule is.. NO WEDDING TALK!
I think that cold feet is a function of the constant discussion of the wedding, the guests, the costs, the this and that - but if you get a chance to get back to the two of you...
You'll remember why you fell in love in the first place.
Give it a chance.