Why can't Tim forget what he has done?

In the Things They Carried, the thing
Tim carries most is memory.  Cross says to his
friend:

'You
writer types,' he said, 'you've got long
memories.'

Ever
since Linda's death, when he was a child, O'Brien has been carrying around the "lives of
the dead."  While other soldiers, like Bowker, go crazy from the burden of memory and
kill themselves, O'Brien uses storytelling to make sense of the senselessness of
death.

O'Brien feels responsible in the deaths of Kiowa and
"The Man I Killed," and so to help him relieve the guilt, he creates fiction in which
he's not the only guilty party.  He creates a shared ownership in all the death.  "I"
becomes "we."  In this way, O'Brien creates his own
collective katharsis--he purges his own pity and fear of death and
shares it with others.

So, to forget is to dishonor, not
only the dead, but the storyteller.