The Blues skipper received his marching orders midway through the first half for kneeing Barca forward Alexis Sanchez in the back off the ball.
Despite being down to 10 men, Chelsea managed to emerge from the Nou Camp with a 2-2 draw to book their place in the final with a 3-2 aggregate win.
Terry initially made a statement claiming that Sanchez had brought the attack on himself by checking his run, but the former England captain wisely changed his story after seeing replays and apologised to his team-mates for "letting them down".
After viewing a replay of the red-card incident, Terry said: "Sanchez was darting in behind me. I've seen the replay and it does look bad.
"I'm not that type of player to intentionally hurt anyone. I've raised my knee, which I maybe shouldn't have done in hindsight. But hopefully people who know me as a person, as a player... I'm not that type of player.
"I'm disappointed but delighted for the lads. To come here and play the way they did and get the result they did with 10 men... I feel I've let them down. I've apologised to them and I want to apologise to the fans as well.
"At the time, I was bewildered because I was trying to protect myself a little bit but looking at it on the replay, I've no complaints. I've let the lads down.
"They've performed brilliantly so hopefully this doesn't take it away from the players. This is what this football club deserves. We deserve to be in the Champions League final. The boys were excellent and I hope the incident doesn't take away from how hard they worked."
Terry will miss the final, as will Raul Meireles, Ramires and Branislav Ivanovic, who were all booked during what was a feisty encounter. Gary Cahill may also miss the match after leaving the pitch around 10 minutes into the game with an apparent pulled hamstring.
Barcelona defender Gerard Pique also made an early exit from the match but has been given the all-clear after being taken to hospital as a precaution following a heavy clash.
"Gerard Pique underwent various tests which ruled out any injury," Barca said on their website after the Spain international collided with team-mate Victor Valdes in the 17th minute.
"The player will remain under observation until Wednesday," the club added.
Pique played on until the 25th minute before signalling he could not continue and was replaced by Daniel Alves.