General

Stolen Silver Gamertag Mocks me

So, one day I made a Spare Gamertag for Castle Crashers.
2-3 years later somebody decided to Copy my Main Gamertag in every way, altering it to insult me. . . WITH THAT OLD Gtag.

He sends my friends messages, makes fun of me as the Party laughs it up at the Info he put up.
I ussually wouldn't mind, but he brought my Personal Life into it.

I Assume its one of my friends, but that's not the Point.
I wanna know how it happened, and what I can do to Stop this annoying kid.

I went on the Gtag itself, deleted all the Stuff, and he returned with it again.
I had also put a "LIVE Pass Code" but since its Silver I guess it doesn't matter?

What can I do? It's pretty annoying.