Floyd Mayweather … Witnessed Murder-Suicide on FaceTime

EXCLUSIVE

Floyd Mayweather is reeling tonight … because he was on FaceTime with one of his best friends when the guy pulled out a gun, shot his wife and then killed himself … TMZ has learned.

Sources tell us … rapper Earl Hayes called Floyd on FaceTime Monday morning in a rage, over claims his wife — VH1 star Stephanie Moseley — had been unfaithful.

According to…