I have it in the back of my mind that accidents on islands often go 50/50 as proving who was in what lane etc is difficult to prove.

Picture will help and making sure your sketches to the insurance company where each car was will help and picture of road markings, lane etc so they have a clear idea of what went on.

Was she on the island or was she entering from another lane? If she has come onto the island and hit you as you crossed it then it should be clear cut as she has entered without checking and not given way.