Q: me and my wife using iphone on same iTunes account

you can't it's done by design

if you wish to share apps use family sharing Set up Family Sharing - Apple Support

if you keep using the same appleID you will keep getting call history and all the same iMessage and not be able to facetime each other

in the world if apple 2 devices using the same appleID is the same person the appleID is like a socialsecurity number

that happens to my iPhone, my 2 kids, iPad and macbook pro

heres what you do

Settings> Messages> Send and receive>

then for you your number will not be highlighted but your wifes will so just click on it and make sure the check mark isn't next to it and then on the bottom it says start new conversations from and make sure your number has the checkmark

** if you use FaceTime make sure the email isn't checked (if it is then when they FaceTime to your email all your devices that have FaceTime app will ring)

i have to do this every time we update

we each have our own iCloud email but for the apple id we use the same email, it keeps us linked yet our backups are separate

hope this helps

you're welcome I'm glad it helped