There are times when 'to' and 'for' can be used interchangeably.  This is one of those times.  So it would be correct to say, "English is very difficult to me" or "English is very difficult for me."  (You would not need to use the article "The").  

Las preposiciones con los verbos es algo que nos cuesta a todos bastante, personalmente, interpreto (ya te digo es opinión personal) que difficult to sería dificil de "it's difficult to explain" y difficult for sería como dificil para "it's difficult for you to do it" 
No se si te vale de ejemplo