Mate its a fat rip, the moment he got your IP it was over. When you joined his party he probably got your address as well. Its super scumy that there are people like that. I know this because in ARK SE someone did that to me, they invited me in to a party and pulled all my info. I had to call me internet provider to change my IP.
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Best option I looked up was Report to Xbox and another go to my local FBI station and file the attack/complaint. Funny thing is, on Destinytracker all his history has at least one disconnected in every match/ pvp comp/ and strike. This guy has been doing this for a long time.