I know that the above quote might be difficult for some of you to hear on occasions but unfortunately that is the only way to look at it. You have to positive. You have to smile and think of the best.
It is difficult and it is not the best situation but you just have to go over in your mind (not too much) what you did and what the other person did and then think what you would do differently in the future.
If you can learn from that then all power to you and you can go onto bigger and better things.
One thing I will advise you to do is not to display that stiff upper lip. I think that emotion is good as it acts as a release. Let it all out if you have too. You will feel better and let you get on with it.