You can forget your native language only by forgetting yourself, losing your self-identity, destroying your personality and becoming mentally ill. Maybe then you'll forget (although that's still a question!), but you'll definitely start biting! Believe me, my 'medical' philological experience has included many such 'patients' who have contracted the infection of 'derussification'! You will howl at every sign written in Russian, at every Russian word, even at the strumming of a balalaika!