Create a new Apple ID for one of the devices to use for iCloud. You can change the account info. By going to:
Sign in to iCloud with the new Apple ID. When you download apps or backup to iTunes you will still use the shared iTunes account but your info will be kept seperate in iCloud, effectively this will stop the two devices from merging info.
I've tried to create new apple id but was unsuccessful because it would not let me use my email address, saying that it is already associated with an apple id. I really don't want to create a new email. I tried editing apple id to take my email address off as secondary email but it wasn't even on there. Only email address I see associated with that account is my husbands.
I can't explain why Apple would say there is and Apple ID associated with your email if you never created one, that is beyond me, however if there is an Apple ID associated with your email you can use the following link to find out and recover the needed information to use the account.
After the page opens on the right side at the bottom is the option to find out if you have an Apple ID.