Literal translation:
* Я твой худший кошмар. (Ya tvoy khudshiy koshmar.) - This is the most direct and literal translation. It emphasizes the "worst nightmare" aspect.
More colloquial options:
* Я воплощение твоего самого страшного кошмара. (Ya voploshcheniye tvoyego samogo strashnogo koshmara.) - This means "I am the embodiment of your worst nightmare," emphasizing the idea of being the source of fear.
* Я все, чего ты боишься. (Ya vse, chego ty boyishsya.) - This translates to "I am everything you fear," emphasizing the comprehensive nature of your fear.
* Ты никогда не избавишься от меня. (Ty nikogda ne izbavishsya ot menya.) - This means "You will never get rid of me," emphasizing the enduring nature of the fear.
The best choice depends on the context and the specific meaning you want to convey.