Do you lose your temper?

Exactly, people only see a part of what you are most of the times. Those we assume to be happiest in this world just from their conduct and countenance may actually be facing the toughest times ever. Sympathy is a feeling that evokes anger because it makes a person feel less than or inferior to others. It is good to have sympathy and pity towards people who suffer but I for one would never show it openly to them. Instead, offer a helping hand but in a way that preserves and admits their dignity. And yes, what you say about exhibiting your weaknesses is very very true. Most people in this world take great pleasure in mocking and picking at you. Laying bare the weak side of you before such people gives them an opportunity to take its undue advantage. That's why, I feel it is better to mask your true personality before strangers.