A word worth to keep...

As usual, I am busy visiting other blogs when suddenly a quote from one blog caught my attention... it says "It is hard to tell if a man is telling the truth when you know you would lie if you were in his place" I remember that I heard that line a couple of times from a friend. And yes I believe that this is true.
In my life, I have faced a lot of pain and heartaches, after giving it a thought, I realize that I dont know what to believe anymore. Not because, I know I was treated like a fool or I cant trust the people around me... but because I know there are situations that it will be more complicated if you tell the truth.
How about you? What do you think about this line?

"It is hard to tell if a man is telling the truth when you know you would lie if you were in his place"

To say or not to say

Call me Sunshine.
My story is simple, yet I want to ask opinions.
Here it goes...

I have two best friends. They had a relationship before. Eversice, I have a feelings with my best friend (the boy). Now that they are already break... I wonder if it is ok to let him know. I am afraid that he would not talk to me again. I think that this is my chance to let him know... before he enters in another relationship.
I also dont know how the girl (his ex and my best friend) would react if she will know about it. But I really love him.
Please give me your opinion