It's not clear from your question as to whether she has now stopped ignoring you, or if she has ignored you ever since that fateful day. If she is now talking to you, I think you need to talk about why she did this to you. It might be a difficult conversation, but it is important to have it with her. If she is still ignoring you, my first guess is that she thought she was ready for sex with you, but then when it was about to happen she got scared or changed her mind and didn't know how to tell you. he more time passed, the harder it would be for her to fess up to you what had happened. I would suggest that you contact her and make it clear that you don't have any expectations of her. See if you can go and have a coffee during the day so that she knows that all you are going to do is talk. If you do get the chance, it is very important that you listen carefully to her, make her feel safe and avoid being judgemental towards her.