Heidi I'm so sorry this happened, I really don't have useful advice 'cause my wedding is not at an all-inclusive, so I don't care where my guest are staying.. I did a room block but I'm getting that back when people start booking and if not enough people books I'm getting that money deduced from the food bill..
Maybe what you can do now is think thing throughly.. if you thing you are able to do it, save to make the deposit or put it in your credit card.. if not, think about changing locations or eloping.. keep in mind that the important thing is to get married.. of course you want to celebrate but people sometimes don't appreciate what you do for them.. think about what you and your FI really want and need to do..