anyone having a destination wedding?

I'm having a destination wedding on 11/25/2006 in Cancun Mexico. I don't know if at this point i should mail invitations, announcements, or make phone calls. We only want a max of 25 guests (incl. family & closest friends), but out list has grown to about 85. More than half of that we're expecting to decline. I don't know what the etiquette is for this. I feel very lost and want to give up on the whole thing. If anyone can give advice, or knows anyone who has had a destination wedding that can give advice. Please help.
Thanks. Yi-Fon