To stop texts on all devices, turn off Text Message Forwarding in your iPhone's Settings for SMS/MMS, and sign out of iMessage on other devices or disable Messages in iCloud to stop syncing iMessages (blue bubbles) across your Apple ID, ensuring only your primary device gets texts.
If you want to limit Messages to one device, you must sign the account out of Messages on the devices you no longer want to receive messages on, and turn off Messages in iCloud. Do one of the following: On your iPhone or iPad: Go to the Settings app > Apps > Messages, then turn iMessage on or off.
Ensure "Share Across Devices" setting is "OFF"
If you have an Apple Watch and shared your Activity rings with someone, you can choose to stop sharing. On iPhone, go to the Activity app , then tap Sharing. Tap a person you share with, tap their name, then tap either Remove Friend or Hide my Activity.
Remove your associated iPhone or iPad
Tap your name, then tap Media & Purchases. Tap View Account. You might be asked to sign in. Scroll down, then tap Remove This Device.
You and your wife might be sharing Apple Accounts. Each person should have their own Apple Account, as it links your iCloud data (messages, emails, photos, etc.), Media & Purchases, as well as personal information to your personal devices.
iCloud exploitation
Your iCloud account is a gateway to all your synced data, including text messages. Someone can spy on your messages by: Logging into your iCloud account from another device to view message backups. Using a shared Apple ID (common in families) to receive your iMessages on their device.
On your iPhone or iPad, go to the Settings app > Apps > Messages > Shared with You, then turn off Automatic Sharing or turn off Shared with You for a specific app.
Go to the Settings app on your iPhone. Tap Apps, then tap Messages. Tap Text Message Forwarding, then turn on any devices you want to include. If any devices aren't appearing in the list, see the Apple Support article Forward text messages from your iPhone to other devices.
You do not have to create a new ID. When you activate the new phone, just don't restore the backup of the iPad or don't download your purchased content to the device. You can go to Settings>iCloud>Photos>My Photo Stream>Off and any photos that you take with the phone will not transfer to the iPad.
Limit Messages to one device
How To Manually Unlink iPhones From iCloud. Step 1: Shut down the device. Step 2: Go to icloud.com, then select Find iPhone > all devices. Step 3: Browse the list of devices, then select the one you want to unlink.
Open the Settings app. Scroll down and tap on Screen Time. Tap on Share Across Devices. Toggle off the switch for Share Across Devices.
Your husband's phone appears to be connected to yours because you're likely using the same Apple ID, Google account, or cloud storage at the device level. Features such as shared photos, messages, calendars, or built-in location sharing services can also make it seem like the phones are linked.
How to turn off notifications on your iPhone, iPad, and Android device