How do I find the correct IP address due to potential hacking

I am now using my government phone unfortunately and it is not secure. My ex-boyfriend had the same phone number previously with a different phone. I guess with these phones, they keep the same phone number you created with the original account for every new phone given (2 years ago created the account). I reported the phone lost/stolen due to him taking without permission when we split. I received a new phone with his old number months later. I need to figure out what my IP address is particularly for this new phone. Just in case he has access somehow to the old phone number. Curious does he now have access to my new email which was created on the new phone, inadvertently not knowing it was his old number. He is a hacker. He keeps showing his ugly presence. I already caught him placing a $1200 order on my old sprint account with my sons old phone that had access to the sprint app. I already got robbed numerous times by someone on cash app through his old phone number.
I realized after creating an account for this issue that this wasn’t the correct site. Sorry guys. Looks like I have a lot to learn.