I don’t want to share my emails with anybody else

With family sharing you can share the purchases, the subscriptions, the cloud storage , but you are not sharing your Mail or the content of iCloud. If you want you can share selected documents or your Photos Library, but you do not have to do this.

Family Saaring is just a way to save money by sharing the purchases and subscriptions among family members, without having to use the same AppleID, as the subscriptions and purchases are tied to the AppleID, so everyone can have an own iCloud Mail account.

Emails are not shared when using "Family Sharing."

Very thorough response when compared to my answer! Had I seen that first I would not have replied.