Who Do I Have To Invite To My Wedding?

I discovered you can do a wedding at Disney for under 10K if you choose the package for only 20 people(bride and groom included). I’m totally fine with that small of a group! And my groom doesn’t care either way, he just wants me to be happy. However, his mom seems to want to invite the entire state of Oklahoma and my mom wants to invite anyone and everyone she’s ever met! How can I tell them I don’t want that many people there because I’d rather have the Disney wedding than people I don’t particularly care about show up? Also, how many people do you think would honestly RSVP “yes”? Please help!