extreme emotions

I am selfish, but i dont want to be.
I feel extreme guilt when i treat someone badly.
Even the slightest bit.
Eg, when i look at a person and say "what" when he/she is looking at me.
I would feel extremely guilty after saying that.
And my mood for the day would be totally ruined.
I laugh when others are being made fun of.
But i do not want to be made fun of.
I would feel terribly miserable.
I do not know how some people can do it.
To be able to treat someone else like dirt and then after that, just shrug.
Maybe thats why i am always siding with the less fortunate.
I am probably one myself too.
I am however selfish too because sometimes, my patience with such people will be lost.
However, i would feel extremely guilty after that.