husband and i share an itunes account. He receives my messages if he turns on imessage. Turn it off and he receives nothing over wifi? Frustrating!

Wwanddi,

Consider using Family Sharing - Apple Support.

I can't set up another iTunes in my name because my email address (and name) are on our joint account.

Frustrating!

To keep things seperate you need two Apple IDs. If one of you needs to add an iCloud email address in order to create the additional Apple ID, then do it.