Is it my place to tell?

About a year ago I discovered that someone who works with me is being cheated on,but I said nothing to the person.I do believe what in the dark always shows in the light ,soon I knew he would get caught and he was.
Yes ladies its the guy ,when HURTFUL told me this morning what had happen I look at her with a normal face ,was I to act surprise ?HURTFUL said you knew didn't you ? I said yes with no hesitation ,then the question was ask why didn't you tell me ?and I replied "it was not my place to tell"but always said to myself if HURTFUL was to ever figure it out by herself and ask for my input I would have told her,the reality is what it is ,she can take my information what I give to her and do as she may.It was not my place to say anything and I still believe so,the reason I didn't use the word friend is because HURTFUL is just someone I have to deal with on a daily basis,we talk work related stuff. Its still a sad thing because I believe one woman cry is all women cry.Wish HURTFUL all the best in whatever decision she makes.