first of all I would like to offer my sincere condolences...how terrible.
I think maybe they were sincere in the beginning, but by the sounds of it are understandably angry about what has happened to there brother, it must be stirring up all sorts of emotions for them and the easiest one to take it out on is you. They must be hurt that you left when they were little, so the anger they are feeling right now is easily aimed at you, I can understand why you acted the way you did at the trial as you didnt want to impose yourself, but maybe they took it as you didnt care enough? I would try writing to them explaining exactly how you feel and why you acted the way you did at the trial, you have nothing to lose and so much to gain...best of luck! x