Step son advice

I'm 25 weeks pregnant which means my baby will be 10 months old when I marry my fiancé. She will obviously come on the honeymoon with us but my fiancé has a ten year old boy from a previous relationship and he insists he come too! I don't want him to. Not at all. He is very needy and demands a lot of attention. I'm aware that my baby will also demand attention but I see that as my little family and I know it's bad to say but I see the boy as a distraction from us celebrating our wedding and our little family. Am I being unreasonable? Surely I'm not alone in this opinion.