Help

So I got this strange message for a party chat from somebody I don't even know and my stuff is set to private friends and I'm always appear offline so how this person got through to send me a party chat kind of freaks me out that's the first thing that alerted me once I ignored it later on that night when a friend of mine invited me to this new game that I downloaded that he was playing not even 20 minutes later this hacky person came in even though everything set to friends only so there's no way that person could have got in unless they're hacking on my side obviously they would be able to get through to my friends so after that I got scared and deleted the game keep in mind this person only has no friends and only four games on their account and none of them are the ones I have then the next day I was just sitting on my Xbox home screen haven't even been opened up a game yet and everything just started freezing up on my home screen where I had no control on my controller to turn it off and on the only thing I could do is just unplug my box and at that point I'm sitting here thinking okay he got into my Xbox now he has control over everything that's why he keeps freezing it so my friend was like well maybe you should reset it so that's what I did I kept my game since I don't really have a lot of games maybe seven or eight I kept my games but restarted everything else reset and I already changed my password on Microsoft and I changed my pass key which is what I use the sign into my Xbox I've already did all that stuff but my biggest fear is he still might be on there I've been too afraid to turn on my Xbox and play my games being that he still might be there and might freeze me up again I really don't want to have to be forced to change my photo which is a photo of me and change my gamertag just to keep this person from finding me again I shouldn't have to run and hide and be a victim and I figured if they're already in my account I guess it wouldn't really matter right once they're in they're in

:)