Yes, Eddie's advice is sound.
You should have reported this incident to your insurers as soon as it occurred (it is a condition of almost all policies) regardless of her promise to pay. However I cannot seen see them cutting up rough about it as it is a minor incident and unlikely to cost them any money.
Report it to them, let them sort it out with the Third Party (or her insurers as they think fit). There is no room for sentiment when it comes to this sort of thing. I was stung like this many years ago. A "friend" caused some damage to my car, promised to pay as he "did not want to lose his No Claims Discount", eventually failed to do so by which time I had left it too late to deal with it via my own insurers. Once bitten, as they say....