How do i trust thee?

How do I feel when people lie?  Just today i was told that I was mean for not believing that someone is sick.  I was told that the person was hospitalized and so I said "really?".  I don't believe her.  The person looked okay the last time she was here.  I was told that she was overheard throwing up in the loo and i said "I can do that too by sticking a finger to my throat".  "Gosh you are so meaaan" said with that judgmental - joke manner tone of voice.  But if I am allowed to defend my statement or the attitude I displayed towards the situation, first, let me ask to be heard... quite a few times this person lied to me and to others to the extent of compromising the welfare of others, therefore is a selfish act.  One time, this person asked to leave early because of not feeling well (with tears and droopy face and all that) but when this person went out of the building to go home, she was walking in a normal pace. Just on her way out, she spoke with someone in a very normal tone of voice.  oh oh by the way it was really hot outside.  she could have gotten a taxi or a tricycle (motorcycle with side car).  I am a compassionate person.  If ever she really is ill, I will do what I can do to help.  I even suggested that we give her something or visit her. 

I just wish that people can be at least honest and should not lie specially if it will implicate the welfare of others.  I will be a hypocrite if I say that I am perfectly honest.  Of course I lied a few times but for sure, never did I do anything to sacrifice the welfare of others by doing so.