You've kinda made it difficult for a reader to understand what the problem is.
Is someone impersonating you, or your character? Or are you being harassed?
Regardless of the case the best course of action would be to report the person on whatever medium they're using to do these things (forums, in game, social media etc)
Hopefully SE or whoever will ban the person because nobody should feel threatened / uncomfortable on the forums or within the game.
You'll get weird people throughout life in general, but you shouldn't let it get to you.