Nah like Erza said to Kagura, no one but Jellal, Simon, Natsu and herself were there but what probably gave off the impression was the fact that Simon did not return with Erza or Natsu after the incident, so the others including Milliana assumed that Jellal must of killed him. Considering how things were back then, it's natural for them to assume such a thing since Erza never mentioned to them what happened ever, maybe only that Simon was dead but I cannot recall. I would go through the anime but that's quite a few episodes and I can't be bothered lol.
Plus according to Erza's point of view, its her weakness that killed Simon not Jellal.