Do you have Legal cover? they will defend you.
Contatct your insurance company and tell them that you do not want to claim. That way IF she does claim then you have covered your back by telling them.
You will only lose NCB if you claim. IF she does claim however then you will have to try and fight it. Do you have Legal cover? they will defend you. If it comes back 50/50 with the insurance companies then you will have to pay for your own car or your insurance will fix it (your choice) and she will do the same.