Guest List Vent

From the start I told my fiance I didn't want kids at the wedding. He wore me down to one niece and nephew he is close with. But not he told his other brother his other nephew can come. Which now I feel like I have to invite my cousins who are younger children because it would seem rude not to. Before the reason was a no kids weddding, but if my fiance insists on having all the kids in his family there how can I not invite the kids on my side. I know it's not the end of the world, but I just really wanted a fun adult atmosphere. I love my cousins and his nieces and nephews, but didn't feel like having to worry about keeping kids occupied or screaming and/or crying. I'll get over it, I just needed to vent for a minute.