what you are going through is so hard, and you will always have scars from it...unfortunatly people who have not experienced the grief and loss that you have will always find it difficult to undertand. I agree it can be difficult to put up with people always trying to be upbeat - i think that it is just a human reaction that most of us revert to in order to keep going - trying to be positive for others and for ourselves - but sometimes it is not what we want or need! I wish I had an answer for you, but I dont, but dont be afraid to tell people how you are feeling and you dont have to be positive for the sake of others - be true to how you feel.
FG