2 iPhones with same AppleID see each others messages

For several reasones, my wifes iPhone 6 and my iPhone 7 use the same AppleID, but of course have different telephone numbers. Both are on 14.4.1. Under Settings, AppleID, "Name, Phone Numbers, Email", on my phone, her phone number is listed and on her phone my phone number is listed. The AppleID uses my email address which is not set up on my phone; I only have access to that email on my Windows PC. Her phone does have a Yahoo email set up.

The problem is that she sees all my texts. Interestingly, I don't see her texts. (and the ipad set up with the same AppleID sees the texts). I tried removing my telephone number from her phone (Editing "Name, Phone Numbers, Email") but it tells me that I have to turn imessaging off on my phone in order to do that.

How do I fix this problem and have each device have its own separate messaging tied to it's telephone number or is messaging somehow tied to the AppleID?