someone found my ip address and shut down my wifi for the day

I am a regular gamer on xbox, I was playing rocket league and trading with other players. I used the xbox looking for group and posted something I wanted to sell. A random guy was interested and then invited me to his party. I accepted thinking he wanted
something of mine. It was a group of around four people and the guy invited me to play so we could trade. Although I don't know the gamertags or anything. The guy told me he was a hacker and knew what state I lived in and said he knew my IP address as well.
The next thing he said was if I didn't give him one of my items then he would hack my internet and ruin it. Now I obviously thought it was a joke and said for him to say my IP address. I might be tripping a bit but the numbers he said that were my IP address
were identical to my actual ip address. However I didn't check that It actually was my IP address then, I just thought he was chucking up random numbers and he was just using a scare tactic to get some free stuff. I didn't think big of it so I said no and
then he said, "have fun with no wifi." I shrugged it off and continued. After a minute or so, my xbox started to act up, it started to disconnect from the wifi and started lagging. I restarted my xbox and the next thing I knew the wifi was out, saying something
was wrong with the router and I needed to do something. I panicked because the kid was actually right. I went to my dad about this and proceeded to restart my router and do some regular things. My phone, my computer, and my iPad didn't work at all, all of
them saying the internet was down. My dad and I called it quits for the night after around an hour of investigating. I was really mad and went on my ipad for a while, after about 10 minutes, the wifi was put back on. I was relieved and found out my xbox was
good as well. In the morning, everything was good again, except for my brothers pc, it was constantly disconnecting. My parents then called the internet company and did something to put the internet in good shape again. However I am still very scared about
this ip address thing. For one, how in the world did someone get my IP address? Two, how do I prevent it from happening again? Three, do I have to change the ip address again or is there a setting on xbox that makes things more secure and private? Because
I surely don't want anyone or me going through this stuff again.

:)