Someone I don't know added me to the home network. He will know all my phone calls and text messages.

First of all, you should know that if you want to join other people's home network or let other numbers join your own home network, you need not only a mobile phone number, but also a service password or verification code. How can others join your home network if you don't give them the verification code or payment password? This is the first one, and then you say, will he know all your phone calls and messages? I think it's impossible for you to know these things when you join the home network normally, because there is no such service at home, or it can know the calls and text messages of the members of the home network, but you said you didn't know anything, so you joined the home network and didn't know each other, so maybe he couldn't get through by some illegal means! Then he can join your home network, and then he will know that your phone calls and text messages are not impossible, so I think you should first confirm who helped you join your home network.