I would give her some time. Unfortunately if that is what she needs it probably won't help to continue the way things are. It sounds like she also needs to be willing to work on her own insecurities before it can really change. Although I know how hard that can be when you care about someone so much and they shut down.

I would suggest sending her an email if you can stating that you have heard her and will give her space but that you still care about her and she can contact you any time if she wants to talk. And then give her some time. In a month or two if you haven't heard then try a follow-up email to see how she is doing and if she is ready/willing to talk and work through things.