TL;DR – How do I tell a childhood friend that both my parents and I most likely cannot afford to travel for her wedding (to which I am to be a bridesmaid) without making her angry/defensive?
Background
Anne and I have been close friends since we were children. Despite our families closeness, we live ~2,000 miles apart, thus limiting time spent together to a week every summer when they would visit us.
Anne met Jack four years ago. They got engaged, the wedding is 'planned' for two years from now. She asked me to be a bridesmaid shortly after they got engaged last year. They've just recently decided to have a destination wedding.
I moved to their city 3 years ago for college. After graduating I lived with them briefly, for very generously discounted rent.
After a few stressful months of living there, I finally found a job in my field and almost immediately moved into a cheap boarding house.
Problem
Anne and Jack have decided that they're getting married somewhere tropical. Anne had asked me to be a bridesmaid before they chose this location.
As I am working an entry level job and have much student debt, I highly doubt that this time next year I will have ~$2000 to go anywhere. I only get 5 vacation days next year, and none for this year, therefore I would take unpaid days off. My employer is really lenient, I'm almost positive we could work something out for time off. I don't yet have any savings, and am basically still living paycheck to paycheck. As a bridesmaid I would also be paying for my own dress/hair/makeup as well, though I'm not involved in planning the bachelorette party and such.
I've talked to my parents about it, and they don't think they are going to be able to swing it either. From experience, if my parents tell Anne's mother they can't make it, she'll probably get defensive and/or miffed.
Question
How do I tell my friend that both my parents and I probably won't be able to afford traveling such a distance for her wedding, without her taking it personally and getting angry/defensive?