I can understand why you feel that way, and I bet there are some mixed emotions in you about what happened to her and the way her mother reacted.
But she is sad as well, the fact that she is smiling towards you in school is that she wants you to connect with her she is getting upset and confused because you are not approaching her.
She's not backing away, you are, you are frightened of something that is going to happen, not something that has happened yet. If you go to her and tell her how you feel she will appreciate you more, if you continiue to stay away... ten the only outcome is that she will stop loving you, you cannot show that you love someone if they are not there.
I don't think you should be scared anymore, just go up to her and say hi, ask her if you can talk in private and tel her face to face that you never ment harm and that you still like her if she still feels the same.
The reason she wasn't very happy the other day was because she is confused and she doesn't understand why you are, what look to her that your pushing her away.
No more pushing and being scared, just go talk to her, she would like that.
Problem solved.
(don't hide things from her, not even how you feel)