Legal Actions Against Sexual Assault?

Hi. I'm in college and my new girlfriend just told me recently that her ex boyfriend sexaully assaulted her (rape); he held her arms down and covered her mouth...This is obviously the reason that they broke up. Her parents only know that it was a bad breakup and still think she has no sexaul experience whatsoever.
She was too scared at the time to do anything, and now she just wants to let it go. Her parents are religious and her life would be messy if she says anything now.
I know who he is, and I'm thinking about talking to him and recording the conversation. If I get a confession out of him, is it enough to take legal actions? The actual incident happened a year ago so there is no physical evidence. And of course she would be the one who has to sue.
Please help me with this. It's hard for me to see him around campus without punching him.

Please talk to an attorney or even legal aid person. They can tell you if the recorder conversation/confession would stand up in court. The can also tell you if there is a statute of limitation on sexual assualt in your state.

NO no no!!!!
Stay out of it. It is none of your business. I know you mean well but it is totally up to her to take action or not.
She has to be the one to do it. You can't do it for her.
But I would certainly talk to him about it if I were you. I would not punch him under any circumstances. That is called assault and it is illegal and you could get arrested.