Broken bride needs some help... :(?

I think your mistake was getting drawn into a discussion of the nitty-gritty details. People who want to come and can afford to come will come, the rest won't. It's as simple as that. You need to stop explaining why you want a destination wedding, why you want your destination wedding at this particular place, why it costs what it costs - this is what's doing your head in. Just invite the people you want to invite and let them decide if they're going to accept or decline.