Abba_S & Little Froggie – as Little Froggie pointed out, it has to be first-hand knowledge. You have to KNOW that it is true. That is why the fact that it might turn out to be true does not make it permissible. The fact is that you still said something that you did not KNOW to be true, and certainly did not have first-hand knowledge of.
Abba_S: I’m sorry that you feel hurt that I accused you of Motzi Shem Ra. I did so only because according to halacha, on is REQUIRED to tell someone if they are speaking Loshon Hora or Motzi Shem Ra and to try to stop them. One does not lose his cheilik in Olam Haba for doing so, and in fact I would have gone to gehinnom if I didn’t do so. I also was trying to spare you from gehinnom.
Again, I apologize if I didn’t express myself the best way possible. But I did have a chiyuv to say something.