How would someone read my text messages from their phone

Hello him225,

That's a wonderful question! Apple takes privacy and security of their customers products and Apple ID's very seriously. That being said, text messages are specific to your device and wouldn't be accessible on another persons device unless they knew your Apple ID log in information and you use Messages in iCloud, or they had access to your device.

If you think you rapped ID has been compromised, Apple does have a great resource which is linked below that walks through great troubleshooting steps. You can also find these steps listed below. These steps walk through regaining control of your Apple ID.

1. "Sign in to your Apple ID account page. If you can't sign in or you receive a message that the account is locked when you try to sign in, try to reset or unlock your account.
2. Change your Apple ID password and choose a strong password.
3. Review all the personal and security information in your account. Update any information that isn't correct or that you don’t recognize, including:

• Your name.
• Your primary Apple ID email address.* If you need to change your email address, update the features and services that you use with Apple ID, so that each one is using your updated Apple ID.
• All alternate email addresses, rescue email addresses, and phone numbers. 
• The devices that are associated with your Apple ID, if you've already set up two-factor authentication.
• Security questions and answers. If you think they might be easy to guess, you should change your security questions.

4.Check with your email address* provider to make sure that you control every email address associated with your Apple ID. If you don't control the email addresses associated with the Apple ID, you should change the password for the email address or use a different email address. 

5.Set up two-factor authentication for your Apple ID. This additional security feature is designed to prevent anyone from accessing your account, even if they know your password."

If you think your Apple ID has been compromised - Apple Support

If you have additional concerns or questions, you can reach out to apple directly. Their contact details can be found via the link below.

Contact - Official Apple Support

Take care!

The short answer: Anyone you share an Apple ID with, either intentionally or accidentally.