Call xbox support and report him back and tell the moderator on the phone his GT and just talk it through with them. They will work it out. They can be pretty fair, but you will have to tell him you were cursing at him and they'll tell you not to do that again, but they'll pretty much let you off if you explain why you cursed at him.
That is, if anything happens and you are banned, messaged by a moderator, and ect.
Hope everything works out ok, bro.
ALSO, if he was a squeaker then the call support will most likely just ignore his complaint, they usually do with very young kids knowing that they are lesser intelligent and will easily do this kind of thing just for spite.