So first thing's first, if this relationship is serious, you're becoming an integral part of her healing process. Everyone is different but I'll tell you how my experience has gone. Remember that she has to heal and that you can be there every step of the way, but it's her healing, not yours. Be by her side no matter what and support her. You need to be her rock but you also need to know when she needs space.

My wife was raped years before I met her but the damage it caused is going to follow her forever. Just like your significant other, mine refused to involve police. Every year when the date rolls around she becomes more emotional and it causes stress and anxiety. Every year it gets better but that day is always in the back of her mind. Communication, as in any relationship, is so important. Set a basic understanding of what she wants and be able to clearly communicate when something is bothering her. That won't be easy if she's anything like my wife because she's wholly independent and wants to deal with all of her problems on her own. Be there, offer help in any way, listen to her. Actually listen to what she's saying and offer advice. Be able to take criticism and outburst because sometimes it won't make sense. She may be hurting and you may not have the answer, you need to be prepared to walk away. Understand, and also be prepared to explain to her, that you don't have all the answers. Her pain is difficult to understand and you may never fully grasp how powerful and devastating her experience was. Be patient, be kind, love unconditionally and be prepared to be unprepared. It's not easy all the time but I've felt that it's been rewarding to know I made a difference in my wife's healing.

As for the revenge aspect, I struggled with that too. Eventually I got over it. I've learned to understand that I don't have to be the knight in shining armour that gets the revenge for the princess. Ultimately my wife is strong enough to decide whether or not she ever wants to come forward to police. It's her battle and I'd stand beside her if she wanted to move forward. I doubt she ever will but I'd be there.

I've kind of rambled. Hopefully I've helped. Good luck to you and yours.