Racial abuse is very serious. It is unfortunate that you did not report it immediately BUT I suspect a lot of crime victims do not (for varying reasons), so I can understand why it did not happen justicemustprevail. It must be worse as you see this woman whenever you visit your local shop 
This incident happened a while ago, but I think you should still report it to the Police. There were witnesses after all, and even if nothing comes from it, it might help you move on from the situation. Hopefully, it will also be one example for your daughter, and others, and will learn never to put up with abuse from anybody, ever!
I hope the issue is resolved satisfactorily, and that you do eventually come to terms with what happened. I am not surprised that you still feel very angry. It is a normal response to being treated like an inferior being, which is what racial abuse signify. It is about someone treating you as a lesser being based on the 'delusions of grandeur' they hold about their own colour, and your own colour being seen as lesser. Your anger at this is totally justified, and too right! Why should you take it lying down?
Nonetheless, I think you need to do something about this, but should avoid creating problems for yourself. Think very carefully and objectively about what you want to do next. Not easy..
Anything you do should be well thought out, and should be in the best interest of yourself and your family.
I am amazed at the vitriole I have seen on this thread. However I also realise that 'human beings' similar to the 'being' who abused you might also be posting on this thread
. Ignoring them is probably the best way forward.