(1) There are two sides to every story and during a break it off conversation those sides are usually very different.
(2) It is very difficult to not get defensive during a conversation of this nature and if you did get defensive, you shouldn't feel badly, the other person knows why you acted that way.
(3) If you wanted to say that you were sorry and to ask nicely for a second chance and you didn't because your pride got in the way, you can always say that now. If you were with a good person,they should be willing to listen.
(4) Break ups are very rarely final the first time around. If someone cared about you enough to be in it with you and then to break it off with you instead of just blowing you off, then that person should be willing to explore, at least once, if there is still something there or if there is a way to rectify, simplify or alter things.
(5) Even if your feelings got hurt by the person's honesty and you had that "stinging" feeling, try to learn from what they said and effect positive change in your life.
(6) If you think there was a miscommunication or you were judged unfairly or incorrectly, re-open the dialogue and calmly try to explain how you are feeling. If you were with a good person, they should be willing to listen and explore.
(7) If someone cuts you off at the knees and gives you no wiggle room at all, you should be wondering about their ability to connect and their desire to be in a good and communicative relationship because no one's perfect and those that can't realize that all humans have some flaws will go out on hundreds of date and have trouble ending up with someone long term.
PS- Maybe go rent The Break Up with Vince Vaughn and Jen Aniston, so you can add a little comic relief to the situation!