just write your cover note with a photo you taken from the will and say to the best of your knowledge it was in perfect condition when you sent it. your brothers can sort themselves out or their wives. its not your fault and you shouldnt blame yourself, your brothers will do the blaming for you. you dont need to admit to anything because you havent done anything wrong. dont dwell on it, be proud of the way you have handled all this on your own and have a good day