Something I feel like I should add to my post.
There's no harm in talking to the police yourself. They may be able to give you some advice or help. Just fully expect them to say there's nothing they can do unless she comes to them herself. If you can get her to talk to them, they will probably try and persuade her to press charges. That choice is hers, and she really needs to think about it because it means committing to a lot of things. For the record, I think she should talk to the police. I'm not so sure pressing charges is worth it, but it will mean the crime is reported and will make it much easier for her if he tries anything else.
If she did press charges, her rapist wouldn't be immediately informed. What would likely happen is that your friend would need to have a recorded police interview, and assuming you could get her to agree to this earlier rather than later she may be forwarded to a hospital for a physical examination. There's no denying that it wouldn't be a pleasant experience for her.
If the police felt that there was sufficient evidence to prosecute, the accused would then be contacted. From that point on, any attempt by him to make contact with your friend in any way would be breaking the law. He comes anywhere near her, she's perfectly within her rights to call the police. This would be explained to him at the time, and he'd know it as well as she would. On this level, pressing charges might actually make her safer, as it means that if he does try anything else then it's much, much easier to call in the police immediately and have them do something about it.
Assuming he pleaded innocent to the charges, the case would go to court. I'm not going to lie, rape trials are absolutely gruelling. They are unbelievably difficult for the victim. Depending on the precise legislation in your country, there might be some way that your friend could testify by video or wouldn't have to actually look her rapist in the eye while she's testifying. But she'd still have to give a comprehensive description of everything that happened to the court, and be cross examined - the latter in particular is quite unpleasant, they will probably ask very specific question about she reacted at particular points in the incident and so forth.
Assuming this is a first offence and this guy has never been called up on it before, I don't want to overstate the chances of conviction. They're very small. As mentioned, it's very easy to sow reasonable doubt in a rape case. It might be, however, that the court will be able to impose something like a restraining order, so on that level it might still be worth it. But it's a long and gruelling experience and both of you need to be prepared to come out of the end without a conviction, because it's probably not going to happen.
Depending on the guy though, it might be enough. You haven't said much about the specifics of the case, but most people who commit rape don't even fully realize that's what they're doing. Being taken to court for it might actually make him think. Heck, he might even confess to the charges.
On a similar note. If you can get anything beyond a verbal testimony from him. Written letter, sound recording, videotape etc in which he acknowledges the incident as rape then the chances of conviction go right up. The only case I'm aware of in which a person I know secured a conviction happened because the guy wrote a letter apologizing. Without that, he'd have won the case.
