I'm going to ruin my family vacation
Why would you ruin the family vacation?
I just want to be left alone.
If you do not want to go you should sty home and let others have fun. You should be honest with them and let them know before things spiral.
Well I'm going anyway.
If you want to be left alone, then why not just stay away? Just tell them you'll stay home otherwise you'll ruin their vacation.