No. Gossiping with facts is something like, "Did you know that Mary is having an affair with Bob from the office?" when it is in fact true. It is telling the truth about someone that really is neither your or the recipients business.

In your situation, telling the facts is an attempt to right a situation. The telling has value to the person doing the telling (you) and the recipient (the boss) who theoretically, would not want bullying to be going on in his establishment.