My closest friend just ended our very close friendship...?

Alright well my ex girlfriend and i broke up in december. She was my first girlfriend and i was a complete d!&k to her after the break up. She forgave me for that and we became so close after it. For 4 months we became so close, closer than when we were going out. But one day in late april she tells me that she has been raped. Never being in this situation before i didn't know what to say. I didn't want to believe her and all i said was wow continuously. She thought i was laughing when i really wasn't. I know she expected more from me, and i feel so bad, that when ever i see her i cannot help but cry. She hates me now and she has every right to, but i really want to fix this. I really want to gain her trust back, but i do not know how to do it. She means the world to me and i don't want to lose her. I really need help...