For those of you that still want hope that Jin is alive (and personally have no idea if he's alive or dead), I concocted this little theory:

They have to lie about everything in the real world or their family and friends will be hurt that are still on the island. Well, what if by 'You are one of the 2 people responsible for the death of my husband', she meant you are one of the reasons why he is still on the island and so susceptible to death. It's pretty obvious with Jack & Kate that they are not allowed to go back to the Island and Sun is under the impression she will never see her husband again.

We don't have to jump to conclusions, because I think that the writers have made it pretty clear Jin will die and it's almost too obvious to the viewers that he will. I think they'll pull a fast one like they always do and keep him alive. If you do remember his gravestone is marked with the crash date like in Sun's story.