You are the one in denial, the facts have been given you by scientists, structural engineers, the firemen and people that worked in the buildings, they have all told you what happened. There are lots of reputable websites that will explain it far better than we can on a messageboard. We weren't there, we didn't take samples and analyse them, so go the the websites of the engineers who can explain it to you.
It's not up to anyone here to try, you can't grasp it, it's beyond your psyche to take in.
You're scared of finding out what really happened, so you can't let yourself see it.
That's ok, lots of people are like you.