Taking it up officially now based on what some male friends told has the potential to derail your case.
With this guy, what all you would need to do is, next time when he tries his monkey business, make it very evident that you do not appreciate his behavior. He would get his message. If, despite this, he continue to be a monkey, think of making it official. As much as possible, save any message/mail he might send to you. No need to be scared. These guys are actually cowards and have a lot to lose.