I still get very, very angry when I see it. It was shocking, scary and painful to witness.
My (now ex) wife woke me up that morning in tears, saying a plane had crashed into one of the towers. We were watching the live coverage as the second plane came in. I said "There's another plane...." and it crashed into the other tower. My wife started crying, saying over and over "Oh my God, oh my God! Oh those poor people". I said to her "This is deliberate, we're under attack"...
We lived in Euless, Texas. DFW Airport was barely 1 mile to our east and we were used to the noise. Most planes took off/landed to the north or south, but the local commuter turboprops would fly overhead on their way west or to join the pattern for departure elsewhere. As the FAA cleared the skies, it got so quiet. I remember standing in our backyard, the blue skies with no planes at all. Silence. No flyovers, no run-up, no takeoffs, no jet noise at all. Just...Silence.
Still to this day, any re-broadcasts or specials brings it all back. It's like opening a wound. My blood pressure rises, I get so angry. So, I try to avoid them. It's not that I'm trying to forget, I can never do that...it's just how I personally cope with it. I will never forget, but I can avoid re-living it.