If the guy did what you think he did, he should swing. Don't take this the wrong way 101proof, but, "raped" last summer (9 months ago) and suddenly it occurs to her to complain about it?
They were already having sex? Consensually? And how old is the "rapist"? Around the same age, or some 40 year old cradle robber? You said you didn't know her that well, well, what's her history? Hmmmm. Did the guy just dump her and she now wants to pay him out, or did it go down the way you think it did? Don't know, but, I'd want to see a lot more proof before I started tying the hangman's knot. Not asking you to supply the details here on the net, but just think about it before you do something rash.
"Rape" is the easiest thing in the world for a female to complain about, but unless it's a genuine drag off the street rape with all the physical evidence that's readily available, it's just another "he said/she said"...