I agree with other. Your manager action is not acceptable.

Have you ever ask to your co-workers? Maybe they are abused too in different way. If not, try to ask them their opinion regarding her actions to you or her actual behavior.

I still thinking that you should ask her directly what's wrong and why does she do this to you. I think to try send her emails, letter, etc to ask her if you scared or if she's avoid this matter.